Home About us Contact
|
Home About us Contact | ||
|
|
||
Low Survival Rate (low + survival_rate)
Selected AbstractsDiscriminant analysis of autofluorescence spectra for classification of oral lesions in vivoLASERS IN SURGERY AND MEDICINE, Issue 5 2009J.L. Jayanthi MSc, MPhil Abstract Background and Objectives Low survival rate of individuals with oral cancer emphasize the significance of early detection and treatment. Optical spectroscopic techniques are under various stages of development for diagnosis of epithelial neoplasm. This study evaluates the potential of a multivariate statistical algorithm to classify oral mucosa from autofluorescence spectral features recorded in vivo. Study Design/Methods Autofluorescence spectra were recorded in a clinical trial from 15 healthy volunteers and 34 patients with diode laser excitation (404,nm) and pre-processed by normalization, mean-scaling and its combination. Linear discriminant analysis (LDA) based on leave-one-out (LOO) method of cross validation was performed on spectral data for tissue characterization. The sensitivity and specificity were determined for different lesion pairs from the scatter plot of discriminant function scores. Results Autofluorescence spectra of healthy volunteers consists of a broad emission at 500,nm that is characteristic of endogenous fluorophores, whereas in malignant lesions three additional peaks are observed at 635, 685, and 705,nm due to the accumulation of porphyrins in oral lesions. It was observed that classification design based on discriminant function scores obtained by LDA-LOO method was able to differentiate pre-malignant dysplasia from squamous cell carcinoma (SCC), benign hyperplasia from dysplasia and hyperplasia from normal with overall sensitivities of 86%, 78%, and 92%, and specificities of 90%, 100%, and 100%, respectively. Conclusions The application of LDA-LOO method on the autofluorescence spectra recorded during a clinical trial in patients was found suitable to discriminate oral mucosal alterations during tissue transformation towards malignancy with improved diagnostic accuracies. Lasers Surg. Med. 41:345,352, 2009. © 2009 Wiley-Liss, Inc. [source] Modelling hantavirus in fluctuating populations of bank voles: the role of indirect transmission on virus persistenceJOURNAL OF ANIMAL ECOLOGY, Issue 1 2003Frank Sauvage Summary 1Using field data published in the literature, we investigated pathogen dynamics and conditions of persistence in a mathematical model of the bank vole (Clethrionomys glareolus),Puumala hantavirus system. The host population is assumed to have a 3-year periodic cycle. The duration of very low host density is critical for virus transmission and survival. 2Field epidemiological data strongly suggested a transmission of the hantavirus by the contaminated environment. We thus studied whether this ,indirect' transmission affected the virus persistence in the host population. 3The model assumptions were derived from the following conditions found in the literature: (1) there is no additional mortality nor fecundity loss due to the virus in infected hosts, thus the cyclic demographical pattern is not due to the virus; (2) no remission has been observed, thus we did not consider the existence of recovered individuals; (3) adult females are territorial and juveniles disperse to find a new territory and reach sexual maturity. A fragmented landscape was assumed to occur: individuals can live in favourable or unfavourable patches. 4The model was a compartmental model; the population was structured into susceptible or infectious individuals. We considered two age classes, juveniles and adults, and two sites (populations) connected by juvenile dispersal. 5Model dynamics accurately predicted the cyclic trend in disease prevalence as observed in epidemiological studies. They also showed that indirect transmission significantly increased the probability for the virus to persist during the low-density period of the host population. More precisely, even a low survival rate of the virus outside the host was sufficient to decrease extinction risk of the infection by stochastic events. 6Elasticity analysis showed a high robustness of the model to changes in the parameters of indirect transmission but a high sensitivity to changes in adult density. [source] Combining angiogenic gene and stem cell therapies for myocardial infarctionTHE JOURNAL OF GENE MEDICINE, Issue 9 2009Jennifer Pons Abstract Background Transplantation of stem cells from various sources into infarcted hearts has the potential to promote myocardial regeneration. However, the regenerative capacity is limited partly as a result of the low survival rate of the transplanted cells in the ischemic myocardium. In the present study, we tested the hypothesis that combining cell and angiogenic gene therapies would provide additive therapeutic effects via co-injection of bone marrow-derived mesenchymal stem cells (MSCs) with an adeno-associated viral vector (AAV), MLCVEGF, which expresses vascular endothelial growth factor (VEGF) in a cardiac-specific and hypoxia-inducible manner. Methods MSCs isolated from transgenic mice expressing green fluorescent protein and MLCVEGF packaged in AAV serotype 1 capsid were injected into mouse hearts at the border of ischemic area, immediately after occlusion of the left anterior descending coronary, individually or together. Engrafted cells were detected and quantified by real-time polymerase chain reaction and immunostaining. Angiogenesis and infarct size were analyzed on histological and immunohistochemical stained sections. Cardiac function was analyzed by echocardiography. Results We found that co-injection of AAV1-MLCVEGF with MSCs reduced cell loss. Although injection of MSCs and AAV1-MLCVEGF individually improved cardiac function and reduced infarct size, co-injection of MSC and AAV1-MLCVEGF resulted in the best improvement in cardiac function as well as the smallest infarct among all groups. Moreover, injection of AAV1-MLCVEGF induced neovasculatures. Nonetheless, injection of MSCs attracted endogenous stem cell homing and increased scar thickness. Conclusions Co-injection of MLCVEGF and MSCs in ischemic hearts can result in better cardiac function and MSC survival, compared to their individual injections, as a result of the additive effects of each therapy. Copyright © 2009 John Wiley & Sons, Ltd. [source] Management strategies associating batch-graded and size-graded postlarvae can reduce heterogeneous individual growth in Macrobrachium rosenbergii (de Man)AQUACULTURE RESEARCH, Issue 15 2002K Ranjeet Abstract Two sets of adaptive trials were performed to determine the effects of size grading and batch grading on size heterogeneity in cultured Macrobrachium rosenbergii raised in the Coconut Garden channels of Kuttanad, Southern India. In the first set of trials, postlarvae were batch graded on the basis of their hatching order, segregated and grown separately as first-hatched and second-hatched groups. In the second set of trials, postlarvae were size graded as jumpers and laggards and were grown in separate channels. The average weight attained by prawns after 10 months of culture was highest for jumpers (83.11 g) and lowest for the prawns from the first-hatched group (43.76 g). The percentage of males was highest in the population of jumpers (58.23%). Highest production was recorded in the channel stocked with postlarvae from the second-hatched group (103.4 kg ha,1) and lowest production was obtained from the first-hatched group (63.74 kg ha,1). The proportions of undesirable small males were highest among laggards and the first-hatched group: 24.8% and 15.1% respectively. The level of heterozygosity within morphotypes was also high in these groups. Jumpers attained good growth by the end of culture but, because of their low survival rate, this approach was not economically feasible. However, higher production and survival in the second-hatched group improved economic viability. Thus, for better results, stocking with later-hatched groups would be more appropriate than stocking with the first-hatched group. [source] Screening programmes for the early detection and prevention of oral cancerAUSTRALIAN DENTAL JOURNAL, Issue 2 2009O Kujan Background:, Screening programmes for major cancers, such as breast and cervical cancer have effectively decreased the mortality rate and helped to reduce the incidence of these cancers. Although oral cancer is a global health problem with increasing incidence and mortality rates, no national population-based screening programmes for oral cancer have been implemented. To date there is debate on whether to employ screening methods for oral cancer in the daily routine work of health providers. Objectives:, To assess the effectiveness of current screening methods in decreasing oral cancer mortality. Search strategy:, Electronic databases (MEDLINE, CANCERLIT, EMBASE (1966 to July 2005) and CENTRAL (The Cochrane Library 2005, Issue 3), bibliographies, handsearching of specific journals and contact authors were used to identify published and unpublished data. Selection criteria:, Randomized controlled trials of screening for oral cancer or precursor oral lesions using visual examination, toluidine blue, fluorescence imaging or brush biopsy. Data collection and analysis:, The search found 112 citations and these have been reviewed. One randomized controlled trial of screening strategies for oral cancer was identified as meeting the review's inclusion criteria. Validity assessment, data extraction and statistics evaluation were undertaken by two independent review authors. Main results:, One 10-year randomized controlled trial has been included (n = 13 clusters: 191 873 participants). There was no difference in the age-standardized oral cancer mortality rates for the screened group (16.4/100 000 person-years) and the control group (20.7/100 000 person-years). Interestingly, a significant 34% reduction in mortality was recorded in high-risk subjects between the intervention cohort (29.9/100 000 person-years) and the control arm (45.4/100 000). However, this study has some methodological weaknesses. Additionally, the study did not provide any information related to costs, quality of life or even harms of screening from false-positive or false-negative findings. Authors' conclusions:, Given the limitation of evidence (only one included randomized controlled trial) and the potential methodological weakness of the included study, it is valid to say that there is insufficient evidence to support or refute the use of a visual examination as a method of screening for oral cancer using a visual examination in the general population. Furthermore, no robust evidence exists to suggest that other methods of screening, toluidine blue, fluorescence imaging or brush biopsy, are either beneficial or harmful. Future high quality studies to assess the efficacy, effectiveness and costs of screening are required for the best use of public health resources. In addition, studies to elucidate the natural history of oral cancer, prevention methods and the effectiveness of opportunistic screening in high risk groups are needed. Future studies on improved treatment modalities for oral cancer and precancer are also required. Plain language summary:, Screening programmes for the early detection and prevention of oral cancer. More evidence needed to find out whether screening programmes could detect oral cancer earlier and reduce the number of deaths from this disease. Cancer of the mouth and back of the throat (oral cancer) has a low survival rate, largely because the disease is often not diagnosed until it is advanced. Screening the general population for oral cancer might make it possible to detect cases of the disease earlier. The most common method is visual inspection by a clinician, but other techniques include the use of a special blue "dye" and an imaging technique. The review found that there is not enough evidence to decide whether screening by visual inspection reduces the death rate for oral cancer, and no evidence for other screening methods. [source] Secondary or concomitant neoplasms among adults diagnosed with acute lymphoblastic leukemia and treated according to the LALA-87 and LALA-94 trialsCANCER, Issue 12 2007Emmanuelle Tavernier MD Abstract BACKGROUND. Second malignant neoplasms are a serious complication after successful treatment of childhood acute lymphoblastic leukemia (ALL). Although treatment intensity and outcome were not comparable, with improvements in survival it is important to evaluate the rate and the type of second neoplasms in adults with ALL. METHODS. The data from the GET-LALA group were analyzed. A cohort of 1494 patients, aged 15 to 60 years and enrolled in 2 successive multicenter protocols between 1987 and 2002, was observed to determine the incidence of second neoplasms and associated risk factors. The median follow-up from diagnosis was 6 years. RESULTS. By February 2005 secondary or concomitant neoplasms were documented in 23 patients, including 9 acute myeloid leukemias (AML) or myelodysplasias (MDS), 4 non-Hodgkin lymphomas (NHL), 5 skin tumors, and 5 other solid tumors (1 lung cancer, 1 tongue carcinoma, 1 thymoma, 1 condrosarcoma, 1 histiocytosis). Neoplasms developed 0.5 to 13.8 years (median, 4.5 years) after the diagnosis of ALL. There were 22 patients in first remission and 1 was in second remission. The overall cumulative risk of secondary neoplasms was 2.1% at 5 years, 4.9% at 10 years, and 9.4% at 15 years. The cumulative risk of developing a second hematologic malignancy was 1.8% at 5 years, 2.2% at 10 years, 3.3% at 18 years; that of developing a solid tumor was 0.2% at 5 years, 2.8% at 10 years, 6.2% at 15 years. The development of secondary neoplasm was not associated with the use of any specific cytotoxic agent. However, the risk of skin tumor increased with radiation dose and transplantation (P = .01). Overall survival (OS) after the diagnosis of a second malignant neoplasm was 55% at 10 years. However, the median OS in patients developing AML/MDS was 5.7 months. CONCLUSIONS. The data document that adult ALL survivors are at an increased risk of later malignancy. The risk of secondary or concomitant neoplasm appeared higher than that of childhood ALL previously reported in the literature. Considering the low survival rate of this large unselected adult ALL cohort (32% at 10 years) as compared with that observed in childhood ALL, the risk of second malignancy remains underestimated. Larger series with long-term follow-up are necessary, as well as methods of screening and identification of patients at increased risk. Cancer 2007. © 2007 American Cancer Society. [source] Patterns of mortality for each life-history stage in a population of the endangered New Zealand stitchbirdJOURNAL OF ANIMAL ECOLOGY, Issue 4 2009Matthew Low Summary 1Using data from 396 breeding attempts over an 8-year period, we investigated age- and stage-specific survival rates and their modifying factors in a closed island population of the New Zealand stitchbird (or hihi, Notiomystis cincta Du Bus). 2Survival probability generally increased over time; however, at each life-history transition, survival in the new stage started lower than at the end of the previous stage, creating a ,saw-tooth' function of age-related survival. 3The probability of an egg hatching was low (0·73 ± 0·01): most likely a consequence of genetic bottlenecks previously endured by this population. There was strong support for a positive relationship between hatching rate and the subsequent survival of the female parent, and hatching success declining for females > 4 years old. 4Nestling survival probability increased as a function of brood size and days since hatching, and decreased relative to daily maximum ambient temperature and hatching date. Support for models including ambient temperature was greater than for other covariates, with the majority of this temperature-mediated survival effect being restricted to the early nestling stage. 5Fledglings had low survival rates in the first two weeks after leaving the nest, with post-fledging survival related to the fledgling's mass. Two months after fledging, juvenile survival probability plateaued and remained relatively constant for the following autumn, winter and spring/summer breeding season. There was no effect of sex or season on adult survival probability. However, there was strong support for age-specific variation in adult survival, with survival likelihood increasing during the first four years before showing evidence of a senescence decline. 6Within-stage survival increases were likely related to stage-specific selection pressures initially weeding out individuals of poorer phenotypes for the environment specific to each life-history stage. Such a mechanism explains the initial high mortality at life-history transitions; a well-adapted phenotype for one stage may not necessarily be so well adapted for subsequent stages. These patterns are not only valuable for examining life-history theory, but also for understanding the regulation of vital rates in an endangered species and providing a basis from which better population management models and harvesting regimes can be derived. [source] Overwinter mass loss of snowshoe hares in the Yukon: starvation, stress, adaptation or artefact?JOURNAL OF ANIMAL ECOLOGY, Issue 1 2006KAREN E. HODGES Summary 1Overwinter mass loss can reduce energetic requirements in mammals (Dehnel's phenomenon). Alternatively, mass loss can result from food limitation or high predation risk. 2We use data from fertilizer, food-supplementation and predator-exclusion experiments in the Yukon during a population cycle from 1986 to 1996 to test the causes of overwinter mass loss by snowshoe hares (Lepus americanus). In all years, some hares on control sites gained mass overwinter. During the increase phase the majority gained mass, but in all other phases the majority lost mass. 3Snowshoe hares weighing < 1000 g in autumn always gained mass overwinter, as did the majority that weighed 1000,1400 g. Hares weighing > 1800 g in autumn usually lost mass. 4Snowshoe hares on the predator-exclosure + food site gained mass overwinter in all years. Hares on the food-supplementation sites lost mass during the decline but gained mass in all other phases. Fertilization had little effect on mass dynamics. 5Snowshoe hares were more likely to lose mass during winters with low survival rates. Snowshoe hares on the predator-exclosure treatments were more likely to gain mass than were hares on control sites. 6Overwinter mass loss was correlated with maximum snow depth. At equivalent snow depths, hares on food-supplemented areas lost 98 g (± 14·6 SE) less on average than hares on the controls and predator-exclosure treatment. 7Bone-marrow fat was related to body mass and cause of death. Small hares had the lowest marrow fat. Hares killed by humans had higher marrow fat than those killed by predators; hares that simply died had the lowest marrow fat. Hares on food-supplemented sites had the highest kidney and marrow fat. 8Overwinter-mass loss for snowshoe hares is explained interactively by winter conditions, food supply, predation risk and autumn mass. Some snowshoe hares lost mass overwinter in all years and on all treatments, suggesting that reducing body mass may facilitate survival, especially in cases where foraging costs are high energetically or increase predation risk. [source] Evaluation of processed bovine cancellous bone matrix seeded with syngenic osteoblasts in a critical size calvarial defect rat modelJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 3 2006U. Kneser Abstract Introduction: Biologic bone substitutes may offer alternatives to bone grafting procedures. The aim of this study was to evaluate a preformed bone substitute based on processed bovine cancellous bone (PBCB) with or without osteogenic cells in a critical size calvarial defect rat model. Methods: Discs of PBCB (Tutobone®) were seeded with second passage fibrin gel-immobilized syngenic osteoblasts (group A, n = 40). Cell-free matrices (group B, n = 28) and untreated defects (group C; n=28) served as controls. Specimens were explanted between day 0 and 4 months after implantation and were subjected to histological and morphometric evaluation. Results: At 1 month, bone formation was limited to small peripheral areas. At 2 and 4 months, significant bone formation, matrix resorption as well as integration of the implants was evident in groups A and B. In group C no significant regeneration of the defects was observed. Morphometric analysis did not disclose differences in bone formation in matrices from groups A and B. Carboxyfluorescine-Diacetate-Succinimidylester (CFDA) labeling demonstrated low survival rates of transplanted cells. Discussion: Osteoblasts seeded into PBCB matrix display a differentiated phenotype following a 14 days cell culture period. Lack of initial vascularization may explain the absence of added osteogenicity in constructs from group A in comparison to group B. PBCB is well integrated and represents even without osteogenic cells a promising biomaterial for reconstruction of critical size calvarial bone defects. [source] | |||||||||||||