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M C Clark

Publications and source records attributed to M C Clark.

At least 19 recordsLinked to original sources
PubMed1998

Automatic tumor segmentation using knowledge-based techniques.

A system that automatically segments and labels glioblastoma-multiforme tumors in magnetic resonance images (MRI's) of the human brain is presented. The MRI's consist of T1-weighted, proton density, and T2-weighted feature images and are processed by a system which integrates knowledge-based (KB) techniques with multispectral analysis. Initial segmentation is performed by an unsupervised clustering algorithm. The segmented image, along with cluster centers for each class are provided to a rule-based expert system which extracts the intracranial region. Multispectral histogram analysis separates suspected tumor from the rest of the intracranial region, with region analysis used in performing the final tumor labeling. This system has been trained on three volume data sets and tested on thirteen unseen volume data sets acquired from a single MRI system. The KB tumor segmentation was compared with supervised, radiologist-labeled "ground truth" tumor volumes and supervised k-nearest neighbors tumor segmentations. The results of this system generally correspond well to ground truth, both on a per slice basis and more importantly in tracking total tumor volume during treatment over time.

Algorithms↗
PubMed1998

Parenteral vs oral antibiotics in the prevention of serious bacterial infections in children with Streptococcus pneumoniae occult bacteremia: a meta-analysis.

OBJECTIVE: To determine whether parenteral antibiotics are superior to oral antibiotics in preventing serious bacterial infections in children with Streptococcus pneumoniae occult bacteremia. METHODS: Using the MEDLINE database, the English language literature was searched for all publications concerning bacteremia, fever, or Streptococcus pneumoniae from 1966 to January 1, 1997. All nonduplicative studies with a series of children with S. pneumoniae occult bacteremia having both orally treated and parenterally treated groups were reviewed. Children were excluded from individual studies if at the time of their initial evaluation they were immunocompromised, had a serious bacterial infection, underwent a lumbar puncture, or did not receive antibiotics. RESULTS: Only 4 studies met study criteria. From these studies, 511 total cases of S. pneumoniae occult bacteremia were identified. Ten of 290 (3.4%) in the oral group and 5 of 221 (2.3%) in the parenteral antibiotic group developed serious bacterial infections (pooled p-value = 0.467, pooled OR = 1.48; 95% CI, 0.5-4.3). Two patients in the oral group (0.7%) and 2 patients in the parenteral group (0.9%) developed meningitis (pooled p-value = 0.699, pooled OR = 0.67; 95% CI, 0.1-5.1). CONCLUSION: The rates of serious bacterial infections and meningitis did not differ between children who were treated with oral and parenteral antibiotics. The extremely low rate of complications observed in both groups suggests no clinically significant difference between therapies. A study with >7,500 bacteremic children (or >300,000 febrile children) would be needed to have 80% power to prove parenteral antibiotics are superior to oral antibiotics in preventing serious bacterial infections.

Administration, Oral↗
PubMed1997

A causal functional explanation of maintaining a dependent elder in the community.

A causal functional structure demonstrates how a perpetual process, like caregiving, maintains itself. The caregiver functional learning model was used to identify factors influencing caregivers when maintaining dependent elders in the community. These factors include seriousness of illness, power, burden, care quality, self-assurance, an understanding of the elder's needs, and time spent in caregiving. This five-stage theoretical model was tested using a sample of 70 caregivers. Findings supported two of the theoretical relationships: seriousness of illness (beta = .60) with burden (R2 = 0.35), and self-assurance (beta = .36) with time (R2 = 0.18). Three new relationships were added with the empirical model: power (beta = .48) with burden (R2 = 0.52), seriousness of illness (beta = .36) with self-assurance (R2 = 0.11), and burden (beta = .33) with time (R2 = 0.24). A causal functional structure can be used to explain how the phenomenon of caregiving maintains itself.

Activities of Daily Living↗
PubMed1997

Long-term follow-up of post-acute traumatic brain injury rehabilitation: a statistical analysis to test for stability and predictability of outcome.

A high percentage of the estimated 500,000 traumatic brain injuries (TBI) in the US every year occur with young people who will face many years of neurobehavioral and economic consequences. This study examined the long-term stability of outcome after post-acute TBI rehabilitation and possible predictors of long-term outcome based on a 127-item survey of 332 clients up to 14 years post-discharge. Correlational, factor, and multiple regression analysis indicated positive long-term outcome stability following rehabilitation with the exception of vocational status, which decreased over the same time period. A number of possible explanations for this occupational anomaly are suggested. Rating scale scores and latency-to-rehabilitation proved to be better predictors of long-term outcome than demographic data.

Activities of Daily Living↗
PubMed1997

Medical image analysis with fuzzy models.

This paper updates several recent surveys on the use of fuzzy models for segmentation and edge detection in medical image data. Our survey is divided into methods based on supervised and unsupervised learning (that is, on whether there are or are not labelled data available for supervising the computations), and is organized first and foremost by groups (that we know of!) that are active in this area. Our review is aimed more towards 'who is doing it' rather than 'how good it is'. This is partially dictated by the fact that direct comparisons of supervised and unsupervised methods is somewhat akin to comparing apples and oranges. There is a further subdivision into methods for two- and three-dimensional data and/or problems. We do not cover methods based on neural-like networks or fuzzy reasoning systems. These topics are covered in a recently published companion survey by keller et al.

Algorithms↗
PubMed1997

Do oral antibiotics prevent meningitis and serious bacterial infections in children with Streptococcus pneumoniae occult bacteremia? A meta-analysis.

OBJECTIVE: To determine whether oral antibiotics prevent meningitis and serious bacterial infections in children with Streptococcus pneumoniae occult bacteremia. DATA SOURCES: Using the Medline database, the English-language literature was searched for all publications concerning bacteremia, fever, or S pneumoniae from 1966 to April 1996. STUDY SELECTION: All studies that included a series of children with S pneumoniae occult bacteremia containing orally treated and untreated groups. Children were excluded from individual studies if they were immunocompromised, had a serious bacterial infection, underwent a lumbar puncture, or received parenteral antibiotics. DATA EXTRACTION: Three authors independently reviewed each article to determine the number of eligible children and the outcome of children meeting entry criteria. DATA SYNTHESIS: Eleven of 21 studies were excluded, leaving 10 evaluable studies with 656 total cases of S pneumoniae occult bacteremia identified. Patients who received oral antibiotics had fewer serious bacterial infections than untreated patients (3.3% vs 9.7%; pooled odds ratio, 0.35; 95% confidence interval, 0.17 to 0.73). Meningitis developed in 3 (0.8%) of 399 children in the oral antibiotic group and 7 (2.7%) of 257 untreated children (pooled odds ratio, 0.51; 95% confidence interval, 0.12 to 2.09). CONCLUSION: Although oral antibiotics modestly decreased the risk of serious bacterial infections in children with S pneumoniae occult bacteremia, there was insufficient evidence to conclude that oral antibiotics prevent meningitis. Published recommendations that oral antibiotics be administered to prevent serious bacterial infections in children with possible S pneumoniae occult bacteremia should be reevaluated in light of the lower risk of sequelae from S pneumoniae occult bacteremia and newer data concerning side effects from treatment.

Administration, Oral↗
PubMed1996

The elbow joint and its total arthroplasty. Part II. Finite element study.

The stresses in various sections of two-dimensional models of the elbow joint, without and with a prosthesis (the humeral component of a total elbow prosthesis), were obtained using the finite element analysis method. Three parameters were varied: type of applied load; method of fixation of the prosthesis to the contiguous bone; and shape of the head of the prosthesis. The results are discussed with particular reference to stress shielding and overload in the cortical and cancellous bones, respectively, and a qualitative comparison between the present values and those given by previous workers who used three-dimensional models. Comments are made regarding the clinical implications of the results.

Adult↗
PubMed1995

Activation of cytokine production and adhesion molecule expression on THP-1 myelomonocytic cells by macrophage colony-stimulating factor in combination with interferon-gamma.

THP-1 myelomonocytic leukemia cells cultured with either macrophage colony-stimulating factor (M-CSF) or interferon-gamma (IFN-gamma) alone produce, at best, only low levels of interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha). However, combinations of the two factors resulted in at least 3- to 20-fold greater amounts of IL-1 beta and TNF-alpha than would have been predicted by additive mechanisms. This enhanced cytokine production was observed when M-CSF and IFN-gamma were added simultaneously or when M-CSF was added 24 h after addition of IFN-gamma to the cells. Similar results were obtained with fresh human peripheral blood cells treated with IFN-gamma + M-CSF. Cycloheximide treatment of the cultures containing M-CSF and IFN-gamma inhibited the production of IL-1 beta and TNF-alpha. Northern blotting studies revealed no effect of IFN-gamma alone on IL-1 beta or TNF-alpha mRNA production. IL-1 beta and TNF-alpha mRNA expression was observed at 2 and 6 h after treatment with M-CSF or IFN-gamma + M-CSF. Higher TNF-alpha mRNA expression was observed at 2 and 6 h after treatment with IFN-gamma + M-CSF, and higher IL-1 beta mRNA expression was observed at 2 h after treatment with IFN-gamma + M-CSF compared with mRNA levels observed for cells cultured only with M-CSF. These results suggest that the augmented cytokine production resulting from treatments with combinations of M-CSF and IFN-gamma occurs due to increased cytokine mRNA and increased cytokine protein synthesis. In addition to up-regulating cytokines, combinations of IFN-gamma and M-CSF resulted in augmented cell surface expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. This was accompanied by morphological and functional changes that included plastic adherence, extensive homotypic aggregation, and a macrophage-like appearance. These phenotypic changes and enhancements in cytokine expression and cell surface molecule expression may be related to activation of monocytic cells to become cytotoxic effectors by M-CSF and IFN-gamma combinations. In vitro cytotoxicity against A-375 melanoma cells was greatest for cultures that contained M-CSF and IFN-gamma in combination.

Cycloheximide↗
PubMed1995

Rehabilitation technology assessment practices in vocational rehabilitation agencies.

A rehabilitation technology assessment is an essential element in the array of rehabilitation technology services provided for vocational rehabilitation (VR) clients. As a part of a comprehensive survey of rehabilitation technology services in VR agencies, information was collected on current practices in rehabilitation technology assessment. Some variation in length, components included, and professionals involved were found among agencies. A complete description of these assessments as reported by VR agencies is discussed and commonalities in current practice are described.

Consultants↗
PubMed1992

Levamisole causes differential cytokine expression by elicited mouse peritoneal macrophages.

Thioglycolate-elicited peritoneal macrophages from normal C57B1/6J mice were examined in vitro for bacterial lipopolysaccharide (LPS)-stimulated interleukin-1 (IL-1), IL-6, and tumor necrosis factor (TNF) production. Macrophages from mice administered a single oral dose of levamisole (3 mg/kg) 1 to 4 days prior to macrophage harvest demonstrated a twofold enhancement of IL-1 production compared to vehicle-treated mice. In contrast, IL-6 production and TNF production by the same macrophages were inhibited up to 36 and 62%, respectively, compared to production by macrophages harvested from vehicle-treated mice. Similar results were observed when IL-1 production and TNF production were followed in peritoneal exidate cells directly stimulated with levamisole in vitro. The ex vivo LPS-stimulated IL-1 production was enhanced 4 days after macrophage elicitation, whereas TNF and IL-6 production returned to baseline by 72 h after macrophage recruitment and augmentation. No evidence could be found for the presence of inhibitors of TNF or IL-6. The specificity of the IL-1, IL-6, and TNF bioactivities was demonstrated by neutralization with specific antisera. Immunoprecipitation studies of supernatants from biosynthetically labeled macrophages also revealed augmented IL-1 production and decreased IL-6 and TNF, indicating that levamisole may have affected cytokine production at the translational level. Kinetics studies revealed that ex vivo release of IL-6 and TNF by macrophages from levamisole-dosed mice was delayed compared to production of these cytokines by macrophages harvested from mice given vehicle only. The results may explain, in part, the reported ability of levamisole to ameliorate cases of rheumatoid arthritis or other autoimmune and inflammatory diseases by affecting the relative levels of cytokines produced by macrophages recruited to sites of injury, which are associated with inflammation and acute-phase protein synthesis.

Animals↗
PubMed1991

Enhancement of in vitro lipopolysaccharide-stimulated interleukin-1 production by levamisole.

The production of interleukin-1 (IL-1) by the P388D1 mouse macrophage cell line and by adherent peritoneal exudate cells (PMs) was examined. In vitro IL-1 production by P388D1 cells treated with lipopolysaccharide (LPS) was enhanced by coculture with levamisole (0.1 to 10 microM). Oral administration of levamisole (3 mg/kg) to mice also resulted in potentiation of in vitro IL-1 production by thioglycollate-elicited peritoneal macrophages in response to in vitro LPS stimulation. Potentiation was approximately twofold. IL-1 production in the absence of LPS by either the P388D1 cells or the PMs was nil, and levamisole did not directly stimulate IL-1 production in these cases. IL-1 activity in the culture supernatants was measured by thymocyte comitogenic assays. The immunochemical identify of the thymocyte comitogenic activity as IL-1 alpha was confirmed by neutralization with a specific goat anti-mouse IL-1 alpha antiserum. These results suggest that one mechanism by which levamisole acts to normalize and restore immune responses may be enhancing the signals which enable activated macrophages to secrete IL-1.

Animals↗
PubMed1990

Older adults and daily living task profiles.

This paper describes data generated from a comprehensive study in which human factors techniques were applied to the analysis of 25 personal and instrumental activities of daily living (ADLs) performed by 60 older adults (age 55 to 93 years) living in the community. Demand profiles generated from task analysis of video-taped ADLs identify the demands inherent in task activities and the objects and environments associated with them. Examples of four different approaches to examine ADL performance using demand profiles are presented: global descriptions of demands across all ADL tasks, task component profiles, task-specific profiles, and action profiles.

Activities of Daily Living↗
PubMed1989

In what ways, if any, are child abusers different from other parents?

In recent years a variety of alternative theoretical models have been developed to aid our understanding and to guide research in this area. This essay considers in particular the psychiatric model and the social interactional model of child abuse, together with research studies comparing physically abusive and non-abusive families. It will be concluded that research has pinpointed several important distinguishing features in the behaviour of abusive versus non-abusive families. A pattern of behaviour with their child is displayed by abusers that is proportionately more aversive than for non-abusers, and observations of parent-child interactions have revealed qualitative differences in patterns of interaction which seem to be a significant factor in the differentiation of abusive from non-abusive families.

Child↗
PubMed1987

Social support, perceived control, and well-being: a study of an environmentally stressed population.

Interviews were conducted with elderly residents of an area targeted for massive redevelopment. Social support was considered simultaneously with health and personal control beliefs in relation to well-being, and the unresolved issue of the sufficiency of one support figure was explored. Health, control, and support each emerged as independent predictors of after and life satisfaction, and affect was significantly lower for those with no close support figure than for those with one close relationship. The results suggest that one close support figure may be sufficient to promote well-being, but alternative interpretations are possible.

Aged↗
PubMed1986

Characterization of a plasmid in isolates of Corynebacterium sepedonicum.

Lysis of mid-log phase cells of the Gram-positive bacterium, Corynebacterium sepedonicum, by a combination of lysozyme treatment and incubation with alkaline sodium dodecyl sulfate at 56 degrees C led to the recovery of a single plasmid. The plasmid was purified in CsCl density gradients, and its molecular weight estimated to be 31 megadaltons (46 kilobases), as determined from its relative mobility in agarose gels, from its contour dimensions in electron micrographs, and from the size of the fragments generated when it was cleaved with various restriction endonucleases. Thirteen widely divergent isolates of C. sepedonicum were screened for the presence of plasmid, and of these, 11 were shown to harbour a single plasmid at a level of about 30 copies per cell. Cleavage of the plasmid with PstI gave an identical banding pattern in agarose gels for the fragments from all of the plasmid-carrying isolates. The relevance of plasmid incidence and distribution in C. sepedonicum is discussed in relation to the possibility of developing a test for the detection of bacterial ring rot by using plasmid DNA as a hybridization probe.

Corynebacterium↗
PubMed1984

Comparison of the echocardiographic and hemodynamic diagnosis of rheumatic tricuspid stenosis.

Two-dimensional echocardiography has proved to be reliable in the diagnosis of mitral, aortic and pulmonary stenosis. Its role in the diagnosis of rheumatic tricuspid stenosis is still being defined; therefore, the tricuspid valve echograms of 147 patients with rheumatic heart disease were examined. Thirty-eight of these patients also underwent hemodynamic evaluation. Tricuspid stenosis was defined echocardiographically as diastolic anterior leaflet doming, thickening and restricted excursion of the other two tricuspid leaflets and decreased separation of the leaflet tips. Using these criteria, the sensitivity and specificity of the echocardiogram in detecting tricuspid stenosis were 69 and 96%, respectively, in the group of 38 patients who had both echocardiographic and hemodynamic evaluations. However, when the smaller group of 17 patients who had simultaneous right atrial and right ventricular pressure recordings were considered separately, there was complete agreement between the echocardiographic and hemodynamic data. Thus, the two-dimensional echocardiogram is a sensitive and specific test for diagnosing rheumatic tricuspid stenosis. In addition, these data provided an opportunity to determine the prevalence of tricuspid stenosis in this group of patients with chronic rheumatic valvular disease. Tricuspid stenosis was present in 14 (9.5%) of the total group of 147 patients who had two-dimensional echocardiograms, and in 10 (26.3%) of the 38 who had both echocardiographic and hemodynamic studies. In patients with rheumatic heart disease about to undergo cardiac catheterization, an echocardiographic study should prove useful in making the diagnosis of tricuspid stenosis.

Adult↗