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.

SourceResearch connectionFrom yearThrough year

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

At least 343 records · Page 19Linked to original sources

PubMed1987

A practical radiologic approach to skeletal dysplasias in infancy.

Although skeletal dysplasias occur infrequently, the recognition of these disorders is important both for the patient and for genetic counseling. Our present understanding of these diseases has come about largely as a result of continued study by a small group of individuals who have become authoritative experts. This accumulated knowledge, as well as newer methods of antenatal detection, has significantly heightened the general interest in these disorders.

Bone Diseases, Developmental↗

PubMed1988

[Frequent occurrences of an enlarged submandibular gland following interstitial irradiation therapy in patients with cancer of the tongue].

A submandibular gland enlargement produces complications in the diagnosis of a nodal metastasis during the follow-up period in patients who have been given interstitial irradiation therapy for their oral cancers. Thus, a retrospective study has been made of the records of such affected patients, to accumulate knowledge regarding the frequency, the time of appearance, and the symptoms leading to the gland enlargement. Among 155 cases of squamous cell carcinoma of the tongue, 73 cases were selected for this study by the following criteria: (1) the patients were free of metastatic adenopathy, (2) they had been interstitially irradiated, and, (3) they were followed-up without surgical treatment for more than 6 months after the radiotherapy. Gland enlargement was found to have developed in 70% of the studied patients, that is, in 49 of the 73 cases within 9 months after radiotherapy.

Brachytherapy↗

PubMed1987

Muscle glycogen and exercise endurance: a twenty-year perspective.

The scientific revelations of 1967 regarding the relationship between glycogen and exercise endurance set in motion two decades of research mostly oriented toward the practical application of those early findings. It is surprising that, in spite of the considerable time that has elapsed between those initial studies and the wealth of knowledge accumulated since, we still do not know the biochemical mechanism that explains why carbohydrate is essential to the ability of the muscle fiber to maintain high force outputs. It may be that the discoveries of 1967 were so widely accepted and so essentially unchallenged that we narrowed our vision as to the potential mechanisms responsible for the observations reported. The time has come for us to lay this issue to rest and answer the question: Why is glycogen availability necessary to perform prolonged, heavy-intensity exercise?

Animals↗

PubMed1987

Porphyria--the UCT experience.

Several forms of porphyria are commonly seen in South Africa. Much of the knowledge accumulated in this field has been due to the meticulous research of Professor Lennox Eales and his colleagues at the University of Cape Town. Professor Eales headed the Porphyria Research Group, founded by the CSIR in 1957 and upgraded to a Unit by the MRC in 1979, until he retired in 1983. Since then porphyria research at UCT has continued within the MRC Liver Research Centre. We present here a description of those forms of porphyria commonly seen in South Africa, based in part on recent work carried out at UCT and in part on the work of Lennox Eales, to whom we dedicate this article.

Acute Disease↗

PubMed1986

The plasma membrane as radiosensitive target.

The rapidly accumulating knowledge on the structure and function of cell membranes stimulates the relevant radiobiological studies. Several factors rendering the membrane system a radiosensitive target as well as radiation-induced alterations of plasma membrane are reviewed. For understanding subcellular effects the need of projecting physical energy deposition events over the biological scenary in respective volumes is emphasized. The possible role of membrane alterations in the fate of irradiated cell is discussed.

Cell Membrane↗

PubMed1979

Chloramphenicol and the neonate--1979 view.

In a therapeutic tragedy perhaps even more widespread than the thalidomide disaster, untold lives were lost between 1949 and 1958 through the administration of inappropriate doses of chloramphenicol to newborn infants. Sensitive assays of blood levels of chloramphenicol now available make it possible to employ this useful antibiotic avoiding its toxic effects. The author reviews accumulated knowledge about chloramphenicol in the newborn infant.

Adult↗

PubMed1979

New aspects of cell membrane radiobiology and their impact on radiation protection.

Recent developments in the field of the membrane biology of eukaryotic cells have revived relevant radiobiological studies. The supramolecular structures of membranes built up by the various chemical components that ensure certain functions and connections of the cells seem to react sensitively to ionizing radiations. Data concerning those radiation-induced alterations that reflect changes of such features and functions as surface charges, membrane-bound enzyme activities and receptor functions are reviewed. As the new concepts arising from the results obtained so far may have consequences in the theory and practice of radiation protection, a few areas are mentioned where the impact of the relevant accumulated knowledge might be expected to result in practical applications.

Animals↗

PubMed1985

Pharmacologically directed ara-C therapy for refractory leukemia.

During a two-year experience treating patients with refractory acute leukemia with a fixed 12-hour schedule of high-dose ara-C, cellular ara-CTP pharmacodynamics were ascertained in circulating blasts of these patients. A strong correlation was found between achievement of complete remission and cellular ara-CTP levels. We therefore, attempted to improve the complete remission rate in patients with low ara-CTP levels by decreasing the intermittent ara-C dosing interval, thereby raising the minimum ara-CTP level in leukemic cells between doses. This initial attempt at pharmacologic direction of chemotherapy was successful in elevating minimum ara-CTP levels but did not produce an increase in response rate, probably because the total duration of ara-CTP exposure was decreased when the dose intervals were shortened. Currently we are engaged in a new approach based on the knowledge accumulated over the past three years. Patients receive a test ara-C dose from which data on ara-CTP cellular metabolism is derived, followed by a CI of ara-C at a dose calculated individually for each patient. Preliminary results of this approach thus far indicate an increased response rate and a different spectrum of toxicity than that observed with intermittent dose ara-C. Further clinical trials will determine the true effectiveness of this approach.

Arabinofuranosylcytosine Triphosphate↗

PubMed1983

Provocation of airflow limitation by viral infection: implication for treatment.

This paper reviews accumulated knowledge concerning the role of virus infection in asthmatic bronchitis and describes several studies, carried out in the author's department, whose findings have elucidated this and other aspects of its aetiology. Rhinoviruses are associated with asthmatic bronchitis far more frequently than any other viruses, due in large part to their numerous antigenically distinct serotypes. Two host factors appear to be involved in the aetiology of asthmatic bronchitis. Impairment of the defence mechanisms of the lower respiratory tract would permit extension of viral infection into the bronchi, where it causes an inflammatory reaction. Reversible airflow limitation of sufficient magnitude to give rise to wheeze and dyspnoea depends upon the second host factor of bronchial hyperreactivity. Since inflammation is the major component of airflow limitation, beta-adrenoreceptor agonists are of limited value in reducing it, whereas corticosteroids are highly effective. The role of interferon is discussed in relation to prevention and treatment of asthmatic bronchitis.

Adult↗

PubMed1984

Biomechanical considerations in revision arthroplasty.

Accumulated knowledge about hip replacement arthroplasty has identified a number of mechanical factors that contribute to implant failure. The mechanics of component design, materials selection, implant fixation, and response of bone and soft tissue structures to an altered loading environment are variables that influence outcome. Revision arthroplasty presents additional problems of loss of bone stock, cortical perforation or fracture, and implant removal that must be appreciated to prevent recurrent failure.

Acetabulum↗

PubMed1976

[Cerebrospinal fluid diagnosis of multiple sclerosis].

Starting from the knowledge accumulated with respect to the etiopathogenesis and the components of immunoreaction a minimal to maximal program by steps has been developed for the cerebrospinal fluid (CSF) in multiple sclerosis (MS). It is based on fundamental methods (I), special supplementary methods (II), and relatively specific immunological methods (III). For MS five possible conditions of the CSF could be determined from alterations of cells and variations in protein: a (1) typically complete and (2.) typically incomplete immunoreactive encephalomyelitic (encephalitic) syndrome, a (3.) nonspecific CSF-syndrome of low degree and less typical character (in the sense of an acute or subacute irritation syndrome) an (4.) atypical syndrome of a considerable degree, and a (5.) normal condition of the cerebrospinal fluid. The significance of immunoreactive cerebrospinal fluid syndromes to the diagnostic criteria of multiple sclerosis as well as further relatively disease-specific methods (such as the MEM test and MSF assay) of determining cellular immunity, are discussed.

Cell Count↗

PubMed1980

Electron microscopy in the diagnosis of neuroblastoma.

I review the accumulated knowledge regarding the electron microscopy of neuroblastic tumors using a retrospective study of 13 primarily small cell neoplasms for which the diagnosis of a neuroblastic tumor (neuroblastoma, ganglioneuroblastoma, ganglioneuroma) was either considered or eventually established. A fine fibrillary background, even if focally distributed by light microscopy and seemingly not recovered in the thick sections, correlated with the presence ultrastructurally of neuritic processes bearing dense core ("neurosecretory") granules and lucent vesicles. In three cases without any fibrillary background by light microscopy, granule-bearing processes were not found by electron microscopy, and different diagnoses were subsequently established for two of those cases. From the standpoint of diagnosis, the sampling error normally introduced in ultrastructural examinations has not been reported to be a significant problem, nor was it in the present cases. Therefore, in supporting a light microscopic diagnosis of neuroblastoma, neuritic processes containing dense granules with or without lucent vesicles should be documented. Neuroblastic tumors with evidence of maturity, ie, ganglion cell differentiation, had the best developed morphologic features by both forms of microscopy. Schwann cells were observed in four cases, including one neuroblastoma. The presence of these cells by electron microscopy, although absent by light microscopy, may reflect an early phase of tumor maturation.

Adolescent↗

PubMed1995

The history, theory, and present status of brain transplantation.

Many questions remain unanswered concerning fetal tissue transplantation: Which conditions result in maximal graft survival and function? Which patients are best suited for transplantation therapy? Why do some patients improve more than others? Is immunosuppression necessary when transplanting fetal tissues? Even though the science of neural transplantation is still in its infancy, the clinical use of CNS transplantation has been achieved on a worldwide scale. The many unanswered questions demand continued laboratory investigations and development of more clinically applicable animal models. Ongoing clinical trials will provide advancement of technique and generate more questions. The future is promising for CNS transplantation. As experience and knowledge accumulate, treatment of a greater variety of CNS diseases, including degenerative, traumatic, vascular, and developmental disorders, may find therapeutic options in the realms of brain transplantation. Key factors in transplantation which must be defined relate to donor tissue, transplant technique, and recipient status. Improvements in surgical techniques will advance the field, but the key issue remains how to increase cell survival and axonal extensions within the host brain.

Animals↗

PubMed1994

Mind and brain in psychiatric treatment.

Psychological and biological components of psychiatric illness must be integrated to avoid the perils of reductionism in diagnosis and treatment. With the decline of dualism, a number of creative thinkers have conceptualized the mind-body problem in a manner that values perspectives derived from psychoanalytic thinking as well as from the neurosciences. Similarly, modern studies of the etiology and pathogenesis of major psychiatric disorders suggest that only through a sophisticated synthesis of psychosocial and genetic/biochemical points of view can causation be comprehensively understood. In light of this accumulating knowledge, the author concludes that treatment must be informed by psychotherapeutic approaches as well as by pharmacotherapy.

Adult↗

PubMed1994

Gastrointestinal decontamination for acute poisoning by ingestion. Prevention of absorption of toxic compounds.

Gastrointestinal decontamination therapy in the patient with accidental or intentional ingestion of toxic substances has been standard therapy for several decades, although based on theory of presumed action and benefit. As scientific knowledge accumulates in this area of clinical toxicology, old assumptions are being challenged by scientific evidence relating to gastric emptying, efficacy of activated charcoal, and usefulness of whole-bowel irrigation with polyethylene glycol electrolyte lavage solutions. An overview is presented of the scientific data now available. Although realizing the still unresolved controversies, a logical plan is described for gastrointestinal decontamination following acute overdose.

Absorption↗

PubMed1994

[Women's health and ill health from a gender theoretic perspective].

Accumulated knowledge of women's health remains incomplete, and its fragmentary nature may be explained by a variety of factors: the contrived 'invisibility' of women in research, normative male predominance, gender bias, an inadequate female power base, insufficient resources, etc. The health paradox--i.e., the relative longevity of women versus their greater proneness to disease and symptoms--is discussed and two models, a biological/genetic and a sociocultural model, are presented in an attempt to explain it. The adoption of a gender perspective in future research is suggested as a possible mean of eliciting new knowledge in this field.

Adolescent↗

PubMed1994

[Interactions between the nervous and the immune system].

The immune and nervous systems have the capacity to modulate inflammatory processes in an additive, synergistic or antagonistic way. In addition to direct effects, feed-back systems connecting immune and nervous systems exist which provide the basis for a better understanding of the modulation of inflammatory reactions by the central nervous system (nervous as well as neuropsychological influences). It is well established that immunocompetent cells, but also endothelial, epithelial and mesenchymal cells induce and regulate inflammation by production of cytokines. However, the expression, synthesis and secretion of neuropeptides by cells of the immune system or even connective tissue cells has only been recognized recently. These findings indicate that non-neuronal cells in the periphery can feedback to the nervous system by secretion of neuropeptides (e.g. modulation of an afferent signal by interaction of peripherally produced neuropeptides with nerve endings). Nitrogen monoxide has recently been shown to act as an important mediator of inflammatory phenomena and to play an important role in neurotransmission. The rapidly accumulating knowledge of the nature metabolism of this highly reactive substance indicate new therapeutic options in the area of neuroimmunology.

Central Nervous System↗

PubMed1994

Corrosion and other electrochemical aspects of biomaterials.

Metallic materials are used extensively as orthopedic implants, dental materials, sensing elements of bioelectrodes, and other applications. The electrochemical behavior of these biomaterials is of interest for a variety of reasons. The corrosion resistance of an implant material influences its functional performance and durability and is a primary factor governing biocompatibility. Among the aspects affecting biocompatibility are the amounts and forms of released corrosion products and their disposition in the body after release. Electrochemical principles are very useful for understanding the factors affecting corrosion resistance and also form the foundation for many biosensors that measure the concentration of various chemical entities (including released corrosion products and naturally occurring substances). Many electrochemical measurement techniques have been used to study biomaterials for years (e.g., polarization curve measurement), while others (such as polarography and AC impedance methods) have been applied more recently. This work focuses on four main topics. The first is the nature of the body's environment as it affects in vivo electrochemical phenomena, that is, the chemical, mechanical, biological, and bioelectrical phenomena that affect the behavior and performance of biomaterials. The second deals with methodology--the techniques used for corrosion measurement and concentration determination, the appropriate environment (laboratory, cell culture, in vivo, etc.), and experimental problems encountered. The third topic treated is the knowledge accumulated regarding the performance of implant alloys in various applications, for example, the forms of corrosion to which they are susceptible, etc. Finally, improvements that may come about in the future regarding both materials and testing methodology are considered.

Alloys↗