Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Indirect Estimation Technics”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

222 records · Page 13Linked to original sources

Enumeration of leukocyte infiltration in solid tumors by confocal laser scanning microscopy.

BACKGROUND: Leukocytes commonly infiltrate solid tumors, and have been implicated in the mechanism of spontaneous regression in some cancers. Conventional techniques for the quantitative estimation of leukocyte infiltrates in tumors rely on light microscopy of immunostained thin tissue sections, in which an arbitrary assessment (based on low, medium or high levels of infiltration) of antigen density is made by the pathologist. These estimates are relatively subjective and often require the opinion of a second pathologist. In addition, since thin tissue sections are cut, no data regarding the three-dimensional distribution of antigen can be obtained. RESULTS: To overcome these problems, we have designed a method to enumerate leukocyte infiltration into tumors, using confocal laser scanning microscopy of fluorescently immunostained leukocytes in thick tissue sections. Using image analysis software, a threshold was applied to eliminate unstained tissue and residual noise. The total antigen volume in the scanned tissue was calculated and divided by the mean cell volume (calculated by "seeding" ten individual cells) to obtain the cell count. Using this method, we compared the calculated leukocyte counts with those obtained manually by ten laboratory personnel. There was no significant difference (P > 0.05) between the cell counts obtained by either method. We then compared leukocyte infiltration into seven tumors and matched non-malignant tissue obtained from the periphery of the resected tissue. There was a significant increase in the infiltration of all leukocyte subsets into the tumors compared to minimal numbers in the non-malignant tissue. CONCLUSION: From these results we conclude that this method may be of considerable use for the enumeration of cells in tissues. Furthermore, since it can be performed by laboratory technical staff, less time input is required by the pathologist in assessing the degree of leukocyte infiltration into tumors.

Antigens, CD↗

Terrestrial risk assessment for linear alkyl benzene sulfonate (LAS) in sludge-amended soils.

A comparison of the estimated environmental concentration and the effect concentrations (in the laboratory or field) in the receiving compartment form the basis of environmental risk assessments. This paper reviews processes that critically influence the fate of LAS in the terrestrial environment. Concentrations of LAS in sludge are quite high due to sorption to primary sludge, precipitation of Ca and Mg-salts of LAS, and lack of biodegradation under anaerobic digestion. This implies that when sludge is applied to soil e.g. as a fertilizer, considerable amounts of this important surfactant may enter the terrestrial environment. Influence of aerobic situations on LAS concentrations during sludge storage needs further research to allow incorporation into the risk assessment. Aerobic biodegradation in soil is considered the most important removal mechanism of LAS loading to the terrestrial environment through sludge-amendment. Sorption plays a role in determining the residence time of a chemical in the soil, hereby enabling more time for biodegradation to occur. In addition, sorption may affect the expression of effects of surfactants towards benthic and soil dwelling organisms and plants. Another factor that needs further attention is the form of LAS in the environment, which is not similar to the commercial material applied in detergents. The differential sorption and biodegradation of the LAS components lead to a shift in the alkyl chain length (homologue), and phenylisomer distribution towards increased hydrophobicity. Also, occurrence of Ca/Mg-salts in the environment versus the Na-salt for the commercial material critically impacts the extrapolation of effects data obtained in lab studies (mostly performed with the commercial material) to the field. The literature data were used in combination with strategies and methods provided by the European Union Technical Guidance Document in support of risk assessment of new and notified substances (1996) for the prediction of environmental concentrations of LAS entering the soil system through sludge applications. Soil biodegradation is an essential, necessary element for the PEC-calculations of LAS. The initial realistic worst case assessment presented indicates no human health risks exists with indirect exposure to LAS through either food or drinking water. Also, current LAS use does not pose a risk to terrestrial organisms such as plants and invertebrates.

Alkanesulfonic Acids↗

Estimation of early childhood mortality using preceding birth technique in a community-based setting.

The preceding birth technique, an indirect method for estimating early childhood mortality based on ascertaining the survival of previous children, was applied in rural Ethiopia within a system of demographic surveillance. Trained community health workers acted as interviewers and transmission flow of the routine health information system was used for data reporting. Data were collected for a median 12 month period from 39 sampled villages of Ticho district in Arsi region. From 1064 mothers having at least a second birth, the proportion dead of the last birth was 0.138 (95% CI 0.117-0.150), corresponding approximately to the probability of dying between birth and age two. It approximates to an infant mortality rate of about 100 x 1000 live-births. From 974 mothers having at least a higher-order birth, the proportion dead of the second to last birth was 0.203 (95% CI 0.178-0.228), equivalent to the risk of dying between 0 and age 5. In spite of the progressive migration of the surveyed population, the process and the outcome of the study suggest that PBT may well be inserted into a primary health care information system run by trained community health workers.

Birth Order↗

Influence of tris(4-chlorophenyl)methanol (TCPM) on gap junction-mediated intercellular communication of cultured bovine granulosa cells.

Tris(4-chlorophenyl)methanol (TCPM) is a by-product in the manufacture of technical grade DDT, which is known to alter properties and functions of the female reproductive system. We investigated whether in vitro TCPM has an influence on the function of gap junction-mediated intercellular communication (GJIC) and gap junction protein expression of connexin 43 (Cx43) in cultured bovine granulosa cells. GJIC was assessed by fluorescent dye microinjection (dye-coupling). After a 1-h exposure to TCPM at a concentration of 32 microM, a significant (P<0.05) reduction in dye coupling occurred. The same result was obtained with o,p'-DDT. At a concentration of 32 microM both pesticides were cytotoxic as indicated by significant (P<0.05) increased propidium iodide staining of the cell nuclei. Little or no effect on the stainable pattern of connexons occurred after 1 h incubation time, while after 3 h treatment from 16 to 64 microM TCPM, a significant inhibition in the immunostaining resulted and the concentrations of 32 and 64 microM TCPM were cytotoxic for the granulosa cells. The freeze-fracture electron microscopy resulted in small differences in the morphology of gap junction plaques of cell cultures treated for 3 h with 8 or 16 microM TCPM in comparison to untreated cells. After treatment with 32 microM TCPM, gap junction plaques were very rarely detected and the lateral intramembraneous particles (IMP) distribution of many plasma membranes was strongly altered. Estimation of the cellular parameters may lead to an enhanced understanding of the mechanism of chemically induced toxicity by TCPM, that causes a general toxic effect on granulosa cells. We can conclude that TCPM is a toxic risk in the same manner as DDT.

Animals↗

A comparison of sisterhood information on causes of maternal death with the registration causes of maternal death in Matlab, Bangladesh.

BACKGROUND: To explore whether causes of maternal death can be investigated using the sisterhood method, an indirect method for providing a community-based estimate of the level of maternal mortality, this study compares the sisterhood causes of maternal death with the Matlab Demographic Surveillance System's (DSS) causes of maternal death. METHODS: Data for this study came from the Matlab DSS, which has been in operation since 1966 as a field site of the International Centre for Diarrhoeal Disease Research, Bangladesh. The maternal deaths that occurred during the 15-year period from 1976 to 1990 in the Matlab DSS area are the basis of this study. A sisterhood survey was conducted in Matlab in November and December 1991 to collect information on conditions, events and symptoms that preceded death. The collected information was evaluated to assign a most likely cause of maternal death. The sisterhood survey cause of maternal death was then compared with the DSS cause of maternal death. RESULTS: Cause of death could not be assigned with reasonable confidence for 34 (11%) of the 305 maternal deaths for which information was collected. For the remaining deaths, the agreement between the two classification systems was generally high for most cause-of-death categories considered. CONCLUSIONS: Though cause-of-death information obtained by the sisterhood method will always be subject to some error, it can provide an indication of an overall distribution of causes of maternal deaths. This data can be used for the planning of programmes aimed at reducing maternal mortality and for the evaluation of such programmes over time.

Abortion, Induced↗

The health and well-being of caregivers of children with cerebral palsy.

OBJECTIVE: Most children enjoy healthy childhoods with little need for specialized health care services. However, some children experience difficulties in early childhood and require access to and utilization of considerable health care resources over time. Although impaired motor function is the hallmark of the cerebral palsy (CP) syndromes, many children with this development disorder also experience sensory, communicative, and intellectual impairments and may have complex limitations in self-care functions. Although caregiving is a normal part of being the parent of a young child, this role takes on an entirely different significance when a child experiences functional limitations and possible long-term dependence. One of the main challenges for parents is to manage their child's chronic health problems effectively and juggle this role with the requirements of everyday living. Consequently, the task of caring for a child with complex disabilities at home might be somewhat daunting for caregivers. The provision of such care may prove detrimental to both the physical health and the psychological well-being of parents of children with chronic disabilities. It is not fully understood why some caregivers cope well and others do not. The approach of estimating the "independent" or "direct" effects of the care recipient's disability on the caregiver's health is of limited value because (1) single-factor changes are rare outside the context of constrained experimental situations; (2) assumptions of additive relationships and perfect measurements rarely hold; and (3) such approaches do not provide a complete perspective, because they fail to examine indirect pathways that occur between predictor variables and health outcomes. A more detailed analytical approach is needed to understand both direct and indirect effects simultaneously. The primary objective of the current study was to examine, within a single theory-based multidimensional model, the determinants of physical and psychological health of adult caregivers of children with CP. METHODS: We developed a stress process model and applied structural equation modeling with data from a large cohort of caregivers of children with CP. This design allowed the examination of the direct and indirect relationships between a child's health, behavior and functional status, caregiver characteristics, social supports, and family functioning and the outcomes of caregivers' physical and psychological health. Families (n = 468) of children with CP were recruited from 19 regional children's rehabilitation centers that provide outpatient disability management and supports in Ontario, Canada. The current study drew on a population available to the investigators from a previous study, the Ontario Motor Growth study, which explored patterns of gross motor development in children with CP. Data on demographic variables and caregivers' physical and psychological health were assessed using standardized, self-completed parent questionnaires as well as a face-to-face home interview. Structural equation modeling was used to test specific hypotheses outlined in our conceptual model. This analytic approach involved a 2-step process. In the first step, observed variables that were hypothesized to measure the underlying constructs were tested using confirmatory factor analysis; this step led to the so-called measurement model. The second step tested hypotheses about relationships among the variables in the structural model. All of the hypothesized paths in the conceptual model were tested and included in the structural model. However, only paths that were significant were shown in the final results. The direct, indirect, and total effects of theoretical constructs on physical and psychological health were calculated using the structural model. RESULTS: The most important predictors of caregivers' well-being were child behavior, caregiving demands, and family function. A higher level of behavior problems was associated with lower levels of both psychological (beta = -.22) and physical health (beta = -.18) of the caregivers, whereas fewer child behavior problems were associated with higher self-perception (beta = -.37) and a greater ability to manage stress (beta = -.18). Less caregiving demands were associated with better physical (beta = .23) and psychological (beta = .12) well-being of caregivers, respectively. Similarly, higher reported family functioning was associated with better psychological health (beta = .33) and physical health (beta = .33). Self-perception and stress management were significant direct predictors of caregivers' psychological health but did not directly influence their physical well-being. Caregivers' higher self-esteem and sense of mastery over the caregiving situation predicted better psychological health (beta = .23). The use of more stress management strategies was also associated with better psychological health of caregivers (beta = .11). Gross income (beta = .08) and social support (beta = .06) had indirect overall effects only on psychological health outcome, whereas self-perception (beta = .22), stress management (beta = .09), gross income (beta = .07), and social support (beta = .06) had indirect total effects only on physical health outcomes. CONCLUSIONS: The psychological and physical health of caregivers, who in this study were primarily mothers, was strongly influenced by child behavior and caregiving demands. Child behavior problems were an important predictor of caregiver psychological well-being, both directly and indirectly, through their effect on self-perception and family function. Caregiving demands contributed directly to both the psychological and the physical health of the caregivers. The practical day-to-day needs of the child created challenges for parents. The influence of social support provided by extended family, friends, and neighbors on health outcomes was secondary to that of the immediate family working closely together. Family function affected health directly and also mediated the effects of self-perception, social support, and stress management. In families of children with CP, strategies for optimizing caregiver physical and psychological health include supports for behavioral management and daily functional activities as well as stress management and self-efficacy techniques. These data support clinical pathways that require biopsychosocial frameworks that are family centered, not simply technical and short-term rehabilitation interventions that are focused primarily on the child. In terms of prevention, providing parents with cognitive and behavioral strategies to manage their child's behaviors may have the potential to change caregiver health outcomes. This model also needs to be examined with caregivers of children with other disabilities.

Adaptation, Psychological↗