Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “knowledge accumulation”

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.

At least 1,099 records · Page 61Linked to original sources
PubMed1998

Lycopene: chemistry, biology, and implications for human health and disease.

A diet rich in carotenoid-containing foods is associated with a number of health benefits. Lycopene provides the familiar red color to tomato products and is one of the major carotenoids in the diet of North Americans and Europeans. Interest in lycopene is growing rapidly following the recent publication of epidemiologic studies implicating lycopene in the prevention of cardiovascular disease and cancers of the prostate or gastrointestinal tract. Lycopene has unique structural and chemical features that may contribute to specific biological properties. Data concerning lycopene bioavailability, tissue distribution, metabolism, excretion, and biological actions in experimental animals and humans are beginning to accumulate although much additional research is necessary. This review will summarize our knowledge in these areas as well as the associations between lycopene consumption and human health.

Absorption↗
PubMed2006

beta-Amyloid degradation and Alzheimer's disease.

Extensive beta-amyloid (A beta) deposits in brain parenchyma in the form of senile plaques and in blood vessels in the form of amyloid angiopathy are pathological hallmarks of Alzheimer's disease (AD). The mechanisms underlying A beta deposition remain unclear. Major efforts have focused on A beta production, but there is little to suggest that increased production of A beta plays a role in A beta deposition, except for rare familial forms of AD. Thus, other mechanisms must be involved in the accumulation of A beta in AD. Recent data shows that impaired clearance may play an important role in A beta accumulation in the pathogenesis of AD. This review focuses on our current knowledge of A beta-degrading enzymes, including neprilysin (NEP), endothelin-converting enzyme (ECE), insulin-degrading enzyme (IDE), angiotensin-converting enzyme (ACE), and the plasmin/uPA/tPA system as they relate to amyloid deposition in AD.

Journal Article↗
PubMed1987

DNA flow cytometry as a prognostic indicator in head and neck cancer.

The prognostic significance of deoxyribonucleic acid (DNA) flow cytometry has been investigated for many solid tumors, but few data have been accumulated for squamous cell carcinomas of the head and neck. To our knowledge, we report the largest number of patients (69) with head and neck primary carcinomas to be studied by DNA flow cytometry. In the first part of this study, we reviewed 109 consecutive patients with laryngeal or hypopharyngeal primary carcinomas which were treated at North Carolina Memorial Hospital during the period of 1981 to 1984. The final analysis comprised 139 DNA histograms (mean coefficient of variation: 8.02) on paraffin-embedded specimens from 48 patients. Of the 48 patients with primary carcinomas, 24 had glottic, 18 had supraglottic, and 6 had carcinomas from the piriform sinus. Patients had follow-up for a minimum of 12 months, with a mean follow-up period of 23 months. Twenty-three of the 48 primary carcinomas (48%) were clearly aneuploid, and the remaining 52% were tetraploid (22%) or diploid (30%). We have concluded that patients with clearly aneuploid primary carcinomas had significantly better prognoses than those with diploid tumors (p = 0.008). High DNA amounts (greater than 40% of cells beyond the diploid peak, DNA G1G0) also correlated with a favorable prognosis when compared with low DNA amounts (p less than 0.01), and this remained significant when the clinical outcome was adjusted for staging of the primary site (T), nodal status, and stage of disease. Ploidy was the most significant prognostic variable for the laryngeal group of patients. In the second part of the study, twenty-one patients with oral cavity squamous cell carcinomas were studied in a similar fashion as the group with laryngeal carcinomas. In this group, a low DNA amount, with 40% as the cutoff point, was associated with a favorable prognosis (p = 0.024), and this remained significant while controlling for T, nodal status, and stage of disease. Numbers were too small to permit evaluation of the impact of ploidy in this group, but there was a slight trend toward aneuploidy and tetraploidy, correlating with a poor treatment outcome (p = 0.228). DNA amount was the most significant prognostic variable for the group of patients with oral cavity carcinomas.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2006

Benign variations and incidental abnormalities of myocardial FDG uptake in the fasting state as encountered during routine oncology positron emission tomography studies.

Increased 18fluoro-2-deoxyglucose (FDG) uptake in the myocardium is frequently observed while performing clinical positron emission tomography (PET) body scans for oncology under fasting conditions. This article reviews the normal variations and abnormal appearances of myocardial FDG accumulation which are likely to be encountered in the routine PET studies. Knowledge about the myocardial glucose metabolism and specific abnormalities are indispensable in the interpretation of myocardial FDG uptake.

Fasting↗
PubMed1978

Assessment of the hazards of polybrominated biphenyls.

During their peak use period, PBBs represented under 1% of the total sales of fire retardant chemicals, and very probably would have escaped intensive study if they had not been mixed accidentally with animal feed preparations. Instead, international attention was drawn to PBBs by the state-supervised killing of over 35,000 cattle which had been contaminated with PBBs. Interestingly, low doses of PBBs exert a broad spectrum of toxicological, pharmacological, and biochemical effects despite low acute toxicity. These effects and the intensive bioaccumulation of PBBs derive from their structure and their consequent resistance of biotransformation and high solubility in fat. In rodents, PBBs are teratogenic, immunosuppressive, and potentially carcinogenic. In bovine, rodent, and avian species, PBBs reduce feed intake and induce mixed function oxidases of liver microsomes. The latter effect may be responsible for steroid level changes which underline hormonal toxicities observed in cows, mink, rats, and chickens. The effects of PBBs on humans are controversial, but data suggestive of immunological, skin, and liver disorders continue to accumulate. Concern about the clinical effects of PBBs is heightened by the knowledge that these compounds readily enter the fetus by crossing the placental barrier and can be transferred to newborn children after extensive passage into breast milk.

Adult↗
PubMed1999

The effect of dust lead control on blood lead in toddlers: a randomized trial.

BACKGROUND: Contaminated household dust is believed to be a major source of exposure for most children with elevated blood lead levels. To determine if a vigorous dust clean-up effort would reduce this exposure we conducted a randomized controlled field trial. METHODS: We randomized 113 urban children between the ages of 6 and 36 months: 56 children to a lead dust intervention composed of maternal education and biweekly assistance with household cleaning and 57 children to a control group. Household cleaning was done by two trained lay workers who focused their efforts on wet mopping of floors, damp-sponging of walls and horizontal surfaces, and vacuuming with a high-efficiency particle accumulating vacuum. Household dust lead levels, child blood lead levels, and maternal knowledge of lead poisoning and sources of exposure were measured before and after the intervention. RESULTS: Ninety-nine children were successfully followed for 12 +/- 3 months: 46 children in the lead group and 53 children in the control group. Age and blood lead were similar in the two groups at baseline and averaged 20 months and 12.0 micrograms/dL, respectively. Blood lead fell 17% in the intervention group and did not change among controls. Household dust and dust lead measures also fell significantly in the intervention group. Children in homes cleaned 20 or more times throughout the year had an average blood lead reduction of 34%. CONCLUSIONS: Regular home cleaning, accompanied by maternal education, is a safe and partially effective intervention that should be recommended for the large majority of lead-exposed children for whom, unfortunately, removal to lead-safe housing is not an option.

Air Pollution, Indoor↗
PubMed2005

[Postpartum depression: we know the risks, can it be prevented?].

In the past 20 years, there has been increasing recognition that for some women, pregnancy may be burdened with mood problems, in particular depression, that may impact both mother and child. With identification of risk factors for postpartum depression and a growing knowledge about a biologic vulnerability for mood change following delivery, research has accumulated on attempts to prevent postpartum depression using various psychosocial, psychopharmacologic, and hormonal strategies. The majority of psychosocial and hormonal strategies have shown little effect on postpartum depression. Notwithstanding, results from preliminary trials of interpersonal therapy, cognitive-behavioural therapy, and antidepressants indicate that these strategies may be of benefit. Information on prevention of postpartum depression using dietary supplements is sparse and the available evidence is inconclusive. Although a few studies show promising results, more rigorous trials are required. The abounding negative evidence in the literature indicates that postpartum depression cannot be easily prevented, yet.

Antidepressive Agents↗
PubMed2003

The role of nitric oxide (NO) in stability regulation of hypoxia inducible factor-1alpha (HIF-1alpha).

Hypoxia inducible factor-1 (HIF-1) is a master regulator under conditions of decreased oxygen availability. As a hypoxia inducible transcription factor HIF-1 is a heterodimer composed of the helix-loop-helix-Per-Arnt-Sim (bHLH-PAS) proteins HIF-1alpha and the aryl hydrocarbon nuclear translocator (ARNT) also known as HIF-1beta. The HIF-1 transcriptional system senses decreased oxygen availability and transmits this signal into patho-physiological responses such as angiogenesis, erythropoiesis, vasomotor control, an altered energy metabolism, as well as cell survival decisions. Among recent advances are the discoveries that reactive nitrogen species (RNS), oxygen species (ROS), cytokines, and growth factors participate in stability regulation of HIF-1alpha and HIF-1 transactivation during normoxia. Here we summarize current knowledge and existing concepts that help to understand how NO affects protein accumulation of HIF-1alpha. Considering the fundamental role of radicals, especially NO, as signaling molecules makes HIF-1alpha an attractive target under conditions of NO formation that may be attributed to both, physiology and pathology. Although initial observations showed that NO inhibits hypoxia-induced HIF-1alpha stabilization and HIF-1 transcriptional activation, later studies indicated that exposure of various cells to chemically diverse NO donors or conditions of endogenous NO formation under normoxic conditions induced HIF-1alpha accumulation, HIF-1-DNA binding, and activation of downstream target gene expression. These contrasting situations evoked by NO provide insights into basic chemical reactions, biochemical signal transduction pathways with broad implications for medicine.

DNA-Binding Proteins↗
PubMed1987

Selenite cataract: a review.

Selenite cataract is a fairly recently described, experimental animal model for cataract (1). Selenite cataract has been extensively characterized histologically (2) and biochemically (3,4). The model has been particularly useful for studies on the roles of calcium accumulation and lens proteolysis in cataract formation (4). This review describes current knowledge of the biochemical mechanism for selenite cataract and indicates how the model may be used for further understanding of cataractogenesis in general.

Animals↗
PubMed1999

ADSA Foundation Scholar Award. Biology of dairy cows during the transition period: the final frontier?

The transition period, from 3 wk before to 3 wk after parturition, is critically important to health, production, and profitability of dairy cows. Most health disorders occur during this time. Compared with other stages of the lactation cycle, relatively little is known about fundamental biological processes during the transition period. The regulation and coordination of lipid metabolism among adipose tissue, liver, gut, and mammary gland are key components of the adaptations to lactation. Lipid accumulation in liver may contribute to health disorders and decreased milk production. Knowledge of key control points in hepatic metabolism of long-chain fatty acids is lacking, as is an understanding of the metabolic effects of hormones, growth factors, and cytokines that mediate stress. Recent evidence indicates that supplemental fats or restricted intakes before parturition can induce a coordinated set of metabolic changes in metabolism of long-chain fatty acids, including peroxisomal beta-oxidation, perhaps mediated by peroxisome proliferator-activated receptors. Estimates of the mixture of fuels constituting metabolizable energy in cows during the early postpartum period suggest that supply of amino acids and glucogenic compounds may be under proposed optima, whereas ketogenic and lipogenic compounds and long-chain fatty acids may be in excess. Because dietary fat does not suppress body lipid mobilization, during the early postpartum period supplemental fat may further imbalance the mixture of fuels and lead to decreased dry matter intake. Increased understanding of the biology of the transition period should decrease health problems and increase profitability of dairy cows.

Adipose Tissue↗
PubMed2005

Tissue-type plasminogen activator is upregulated in metastatic breast cancer cells exposed to insulin-like growth factor-I.

The insulin-like growth factor (IGF) system plays an important role in breast tumorigenesis. Breast cancer cells express the type I IGF receptor (IGF-IR) and respond to IGFs in the environment. Tissue-type plasminogen activator (tPA) has been shown to be associated with neoplastic transformation and the invasive phenotype for highly aggressive tumors; however, its role in breast cancer remains unclear. We asked whether there is a relationship between the IGF system and tPA in estrogen receptor-negative breast cancer cells that could contribute to invasion. When MDA-MB-435s breast cancer cells were exposed to IGF-I, tPA messenger RNA (mRNA) was upregulated in a time-dependent fashion. Tissue-type plasminogen activator protein accumulation was also increased in a similar manner. The invasiveness of MDA-MB-435s cells was enhanced in the presence of IGF-I. When the MDA-MB-435s cells were stably transfected with an antisense IGF-IR expression construct, the transfectants expressed high levels of IGF-IR antisense, dramatically reduced levels of endogenous IGF-IR, and a decrease in relative staining intensity for IGF-IR protein. A marked suppression in tPA mRNA expression occurred in MDA-MB-435s cells accompanying inhibition of IGF-IR. When cells carrying the antisense IGF-IR expression construct were exposed to IGF-I, tPA protein accumulation was significantly lower than that of control transfected cells. To our knowledge, this study is the first to show a relationship between the IGF system and tPA. Strategies that target the IGF/tPA pathway could provide alternative treatments for patients with certain types of metastatic breast cancer.

Adult↗
PubMed2002

NKT cell-derived RANTES recruits APCs and CD8+ T cells to the spleen during the generation of regulatory T cells in tolerance.

The induction of peripheral tolerance via immune privileged sites such as the eye requires splenic colocalization of NKT cells and CD1d(+) tolerogenic F4/80(+) APCs, both of which are needed for the generation of CD8(+)-regulatory T (Tr) cells. Whereas tolerogenic APCs secrete the chemokine macrophage-inflammatory protein-2 for the purpose of recruiting NKT cells, the signals responsible for recruiting potential Tr cells and additional APCs to the spleen are not known. Here we examined the ability of CD1d-stimulated NKT cells to produce chemokines that can recruit other cells needed for tolerance. Our results show that NKT cells stimulated by either CD1d-transfected fibroblasts in vitro or CD1d(+) tolerogenic APCs both in vivo and ex vivo produced RANTES in a CD1d-dependent manner. The requirement for RANTES in tolerance was demonstrated by studies in which RANTES blockade in vivo prevented not only APC accumulation in the spleen but also the generation of CD8(+) Tr cells that suppress Th1 immunity. Thus, CD1d-restricted NKT cells provide critical signals for orchestrating the accumulation of cells needed for tolerance induction. These data expand our current knowledge of RANTES beyond its role in Th1 immune responses to show its importance in tolerance induction and add a novel aspect to our understanding of the role of NKT cells in tolerance. Understanding the precise mechanisms involved in tolerance induction may lead to more effective therapeutic strategies for autoimmunity and graft rejection.

Animals↗
PubMed1984

Issues in continuing professional competence of therapeutic recreators.

Entry level knowledge and skills of professionals become outdated with technological advances and the accumulation of practical skills. Participation in programs offering continuing education units (CEU's) has been the most widely accepted way to combat the obsolescence problem and to document life-long learning. However, research has yet to establish improved service delivery as a result of practitioner involvement in such training programs. Credentialing requires reliable and valid measurement of competence over one's professional life. Therapeutic recreators have yet to present a definitive "scope of practice" or to determine the "half-life" of those competencies believed fundamental to practice. The field of therapeutic recreation is void of research on quality assurance alternatives. Thus, there appear to be unresolved issues regarding therapeutic recreators' needs to maintain their professional competence throughout their careers.

Education, Continuing↗
PubMed1999

[The natural history of of the antiretrovirals: the continuum of their evaluation].

Antiretroviral drugs have, as any medical therapy, their natural history. They are born by screening or designing of molecules with activity against HIV, their efficacy and safety is investigated by clinical trials, evaluated by regulatory bodies, used by clinical practice, and finally analyzed by quality of care, economic, social and ethical studies. This flow of information is dynamically accumulated, but it may stop if negative results are obtained. The described knowledge pathway implies that specific methods are needed to answer different questions. At the same time, many decisions have to be taken in order to keep the process flowing, including multiple agents, such as drug industries, government departments, clinicians, health care providers and health policy makers. This paper describes a comprehensive conceptual framework, including the "knowledge" on antiretroviral drugs, the "methodologies" needed to generate them, and the underlying processes of "decision making". It proposes the need for a continuum of assessment of these drugs.

Anti-HIV Agents↗
PubMedDate not supplied

Reactivation of primary hypertrophic osteoarthropathy by bronchogenic carcinoma.

This paper reports 2 cases of primary hypertrophic osteoarthopathy (PHO) which evolved into secondary hypertrophic osteoarthopathy (SHO) under the influence of bronchogenic carcinoma. The patients had a clinical picture of primary hypertrophic osteoarthropathy but without any signs of disease activity until in the last several months when a malignant bronchopulmonary condition developed. This activated all the symptoms: joint swelling; enlarged fingers and distal forearms and legs; moist palms and soles; unpleasant odour of perspiration; and deeper folds of the forehead and nasolabial furrow. A bone scan showed increased accumulation of the radioisotope in specific regions of the skeleton. To our knowledge, no similar cases have been described in the literature.

Carcinoma, Bronchogenic↗
PubMedDate not supplied

Manipulating chemoattractant and receptor genes.

Chemoattractants, including classical chemotactic factors and members of the chemokine superfamily, function as inducers of leukocyte trafficking and activation based on interactions with seven transmembrane (STM), G protein-coupled receptors. These molecules are expressed by many cell types either constitutively or upon stimulation. Considerable knowledge about the pathophysiological role of chemoattractants and their receptors has been accumulated during the past two decades. However, recent studies using transgenic and gene targeting technology have provided a better illustration of the importance and complexity of the involvement of chemoattractants and receptors in leukocyte trafficking, inflammation, infection, immune responses, development, angiogenesis/angiostasis, and malignant tumors.

Animals↗
PubMed1975

[Fatal skin epithelioma in a stomatologist professionally exposed to x-rays].

An epithelioma of the volar face of the right index caused the death of a stomatologist whose skin had been exposed to X-rays for many decades when keeping dental films in place. The casuistics of the clinical picture are dealt with, and arguments are given for its recognition as an occupational disease. The evaluated X-rays dose (the accumulated dose was approx. 2,100 rem, i.e. relatively low) and modern knowledge on radio-medicine are commented with regard to dose-effect relationship.

Aged↗
PubMed1991

[Epidemiologic foundation for population studies of program MZ-XVII].

Epidemiological foundation included: aim of studies, knowledge about epidemiology of thyroid disorders in Poland, evaluation of radioiodine dose accumulated in thyroids of inhabitants of different age living in different par of Poland, information about relative diet iodine deficiency in different parts of Poland and identification of research teams (manpower) capable to carry on population studies. The final identification of epidemiological foundation was proceeded by pilot studies performed in 4 different regions of Poland. Finally it was decided that population studies would be performed in so called Regions of 6 different University Medical Schools (Białystok, Kraków, Lódź, Poznań, Szczecin, Wrocław). The sample will be selected randomly on the base of information from the voting lists (random selection of vovoidoship, then towns and villages, then streets and number of houses, then number of flats. All living in selected flat or house during Czernobyl accident and born between January 1974 and December 1985 (children) and between January 1926 and December 1973 (adults) will be considered "the sample". In all cases the sample will be examined by means of unified questionnaire and protocol of medical and laboratory examination. The same kits (of the same producers) will be used to evaluate serum TSH, T4, T3 and thyroid autoantibodies. The data obtained will be evaluated by unified computerized system. Separate studies involved the sample of newborns exposed to radioiodine during last trimester of pregnancy, found to be euthyroid and given potassium iodide in first days of life. Separate system was also used to investigate effect of radioiodine and of prophylactic dose of potassium iodide in those with past history of thyroid disorders.

Adult↗