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At least 1,135 records · Page 63Linked to original sources
PubMed2000

The use of magnetite-doped polymeric microspheres in calibrating cell tracking velocimetry.

Continuous magnetic separation, in which there is no accumulation of mass in the system, is an inherently dynamic process, requiring advanced knowledge of the separable species for optimal instrument operation. By determining cell magnetization in a well-defined field, we may predict the cell trajectory behavior in the well-characterized field environments of our continuous separators. Magnetization is determined by tracking the migration of particles with a technique known as cell tracking velocimetry (CTV). The validation of CTV requires calibration against an external standard. Furthermore, such a standard, devoid of the variations and instabilities of biological systems, is needed to reference the method against day-to-day shifts or trends. To this end, a method of synthesizing monodisperse, magnetite-doped polymeric microspheres has been developed. Five sets of microspheres differing in their content of magnetite, and each of approximately 2.7 microm diameter, are investigated. An average gradient of 0.18 T/mm induces magnetic microsphere velocities ranging from 0.45 to 420 microns/s in the CTV device. The velocities enable calculation of the microsphere magnetization. Magnetometer measurements permit the determination of magnetization at a flux density comparable to that of the CTV magnet's analysis region, 1.57 T. A comparison of the results of the CTV and magnetometer measurements shows good agreement.

Cells, Cultured↗
PubMed2000

Evidence-based review of the literature on intrathecal delivery of pain medication.

Evidence-based medicine depends on the existence of controlled clinical trials that establish the safety and efficacy of specific therapeutic techniques. Many interventions in clinical practice have achieved widespread acceptance despite little evidence to support them in the scientific literature; the critical appraisal of these interventions based on accumulating experience is a goal of medicine. To clarify the current state of knowledge concerning the use of various drugs for intraspinal infusion in pain management, an expert panel conducted a thorough review of the published literature. The exhaustive review included 5 different groups of compounds, with morphine and bupivacaine yielding the most citations in the literature. The need for additional large published controlled studies was highlighted by this review, especially for promising agents that have been shown to be safe and efficacious in recent clinical studies.

Analgesics↗
PubMed2001

Co-expression of colligin and collagen in oral submucous fibrosis: plausible role in pathogenesis.

The high incidence of oral submucous fibrosis (OSF), a potentially malignant condition of the oral cavity, in the Indian subcontinent is causally associated with commonly prevailing habit of chewing areca nut and tobacco. Knowledge of molecular alterations in OSF is meagre. OSF is characterised by progressive accumulation of collagen fibres in lamina propria and oral submucosa. Colligin/HSP47 is a 47KDa stress protein which acts as a chaperone for collagen. We hypothesized that since colligin plays a vital role in folding and assembling collagen it may be involved in the pathogenesis of OSF. The present study was undertaken in tobacco and areca nut chewing Indian OSF patients to investigate the correlation, if any, between the expression of colligin and collagen type I proteins in OSF lesions. Immunohistochemical analysis showed overexpression of colligin and collagen type I proteins in 16/23 (70%) and 15/23 (65%) of OSF cases, respectively. The hallmark of the study was the significant association between the increased expression of type I collagen and its chaperone, colligin, in OSF lesions (P=0.0494). The data suggest that the increased levels of colligin in OSF may contribute to the deposition of collagen and consequent increased fibrosis in the oral submucosa in OSF lesions.

Adolescent↗
PubMed2001

Resilience among abused and neglected children grown up.

Although an extensive literature has accumulated documenting the maladaptive outcomes associated with childhood victimization, a limited body of knowledge addresses resilience. This paper sought to operationalize the construct of resilience across a number of domains of functioning and time periods and to determine the extent to which abused and neglected children grown up demonstrate resilience. Substantiated cases of child abuse and neglect from 1967 to 1971 were matched on gender, age, race, and approximate family social class with nonabused and nonneglected children and followed prospectively into young adulthood. Between 1989 and 1995. 1,196 participants (676 abused and neglected and 520 controls) were administered a 2-hr in-person interview, including a psychiatric assessment. Resilience requires meeting the criteria for success across six of eight domains of functioning: employment, homelessness, education, social activity, psychiatric disorder, substance abuse, and two domains assessing criminal behavior (official arrest and self-reports of violence). Results indicate that 22% of abused and neglected individuals meet the criteria for resilience. More females met the criteria for resilience and females were successful across a greater number of domains than males. We speculate on the meaning of these findings and discuss implications for the child maltreatment field. Limitations of the study are also acknowledged.

Adaptation, Psychological↗
PubMed1995

Production of polyhydroxyalkanoates, a family of biodegradable plastics and elastomers, in bacteria and plants.

In response to problems associated with plastic waste and its effect on the environment, there has been considerable interest in the development and production of biodegradable plastics. Polyhydroxyalkanoates (PHAs) are polyesters that accumulate as inclusions in a wide variety of bacteria. These bacterial polymers have properties ranging from stiff and brittle plastics to rubber-like materials. Because of their inherent biodegradability, PHAs are regarded as an attractive source of nonpolluting plastics and elastomers that can be used for specialty and commodity products. The possibility of producing PHAs in large scale and at a cost comparable to synthetic plastics has arisen from the demonstration of PHA accumulation in transgenic Arabidopsis plants expressing the bacterial PHA biosynthetic genes. Synergism between knowledge of the enzymes and genes contributing to PHA synthesis in bacteria and engineering of plant metabolic pathways will be necessary for the development of crop plants that produce biodegradable plastics.

Acids, Acyclic↗
PubMed2000

Mechanisms involved in the pro- and anti-apoptotic role of NO in human leukemia.

Nitric oxide (NO) exerts contrasting effects on apoptosis, depending on its concentration, flux and cell type. In some situations, NO activates the transduction pathways leading to apoptosis, whereas in other cases NO protects cells against spontaneous or induced apoptosis. The redox state of the cells appears to be a crucial parameter for the determination of the ultimate action of NO on cell multiplication and survival. Apoptosis is mostly associated with the delivery of NO by chemical donors and with myelomonocytic cells, whereas antiapoptotic effects seem to be related to the endogenous production of NO by NO synthases and is observed more frequently in cells of the B lymphocyte lineage. Pro-apoptotic effects are often observed when NO reacts with superoxide to produce the highly toxic peroxynitrite. Through the induction of damages to DNA, NO stimulates the expression of enzymes and transcription factors involved in DNA repair and modulation of apoptosis, such as the tumor suppressor p53. The latter molecule transactivates the expression of pro-apoptotic genes, such as bax, and that of the cyclin-dependent kinase inhibitor p21, whereas it down-regulates the expression of the anti-apoptotic protein bcl-2. On the other hand, NO inactivates caspases through oxidation and S-nitrosylation of the active cystein, providing an efficient means to block apoptosis. Other protective effects of NO on apoptosis rely on the stimulation of cGMP-dependent protein kinase (PKG), modulation of the members of the bcl-2/bax family that control the mitochondrial pore transition permeability, induction of the heat shock protein HSP 70 and interaction with the ceramide pathway. A defect in the apoptotic process contributes to the accumulation of tumoral cells in leukemia, notably in B-CLL. A better knowledge of the targets of NO would provide efficient means to control cell apoptosis, and hence would possibly lead to the development of new therapeutic approaches for diseases where an alteration of apoptosis is involved.

Apoptosis↗
PubMed2000

Expression of protein tyrosine phosphatase alpha (RPTPalpha) in human breast cancer correlates with low tumor grade, and inhibits tumor cell growth in vitro and in vivo.

Tyrosine phosphorylation is controlled by a balance of tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). Whereas the contribution of PTKs to breast tumorigenesis is the subject of intense scrutiny, the potential role of PTPs is poorly known. RPTPalpha is implicated in the activation of Src family kinases, and regulation of integrin signaling, cell adhesion, and growth factor responsiveness. To explore its potential contribution to human neoplasia, we surveyed RPTPalpha protein levels in primary human breast cancer. We found RPTPalpha levels to vary widely among tumors, with 29% of cases manifesting significant overexpression. High RPTPalpha protein levels correlated significantly with low tumor grade and positive estrogen receptor status. Expression of RPTPalpha in breast carcinoma cells led to growth inhibition, associated with increased accumulation in G0 and G1, and delayed tumor growth and metastasis. To our knowledge, this is the first example of a study correlating expression level of a specific bona fide PTP with neoplastic disease status in humans.

Animals↗
PubMed2001

Medical illustration: from caves to cyberspace.

The human body has been depicted in ancient cave-paintings, in primitively sculpted figures, and through all the ages in various forms of artistic expression. The earliest medical texts were descriptive but not illustrated. Later, as it became clear that knowledge of the human body and all its systems was essential to the practice of healing, texts were accompanied by illustrations which became an integral part of the teaching process. The illustrators included artists, whose interest was primarily artistic, but who were sometimes employed by surgeons or physicians to illustrate their texts. Occasionally, the physicians or scientists accompanied their texts with their own illustrations, and in the last century, medical illustration, in its infinite variety of techniques, has been developed as a profession in its own right. As knowledge was extended, permitted by social and cultural change, as well as by technological advances, the types of illustrations have ranged from gross anatomy through dissections showing the various organ systems, histological preparations, and radiological images, right up to the computerized digital imagery that is available today, which allows both static and dynamic two- and three-dimensional representations to be transmitted electronically across the world in a matter of seconds. The techniques used to represent medical knowledge pictorially have been as varied as the illustrators themselves, involving drawing, engraving, printing, photography, cinematography and digital processing. Each new technique has built on previous experience to broaden medical knowledge and make it accessible to an ever-widening audience. This vast accumulation of pictorial material has posed considerable problems of storage, cataloguing, retrieval, display and dissemination of the information, as well as questions of ethics, validity, manipulation and reliability. This paper traces these developments, illustrating them with representative examples drawn from the inexhaustible store of documents accumulated over more than two millennia.

Anatomy, Artistic↗
PubMed2004

Prodrugs of bisthiazolium salts are orally potent antimalarials.

We created neutral antimalarial prodrugs that deliver bisthiazolium compounds with antimalarial activity in the nanomolar range. These drugs primarily affect early intraerythrocytic stages through rapid, nonreversible cytotoxicity. The compounds are suitable for both parenteral and oral use and plasma promotes rapid conversion of the prodrug into the drug. We demonstrate that very low doses offer protection in a murine model of malaria. The drugs show great potential for curing high parasitemia with short-course treatments. Oral administration of the TE3 prodrug completely cures Plasmodium cynomolgi infection in rhesus monkeys. The drugs specifically accumulate inside infected erythrocytes, block phosphatidylcholine biosynthesis, and interact with hemozoin. To our knowledge, this class of compounds represents one of the most potent antimalarials tested to date. These unique properties signal a promising future for this class of antimalarial.

Administration, Oral↗
PubMed1996

Bitterness in cheese: a review.

Bitterness, the necessary consequence of proteolysis, has been under investigation from different perspectives. This review attempts to give more up-to-date information on the definition of some principal aspects, the relationship between the proteolytic activity and bitter peptide accumulation in cheese, and methods of isolation and detection of bitter peptides. Further knowledge on the physicochemical properties of bitter peptides in cheese as well as in synthetic peptides and the possible control methods for bitterness are discussed. Particular interest in using some strains of lactobacilli or their enzymes as an adjunct in accelerated ripened cheese (ARC) and enzyme-modified cheese (EMC) without bitterness is also described in detail.

Amino Acid Sequence↗
PubMed1996

Expression of recombinant alpha Ains-crystallin and not alpha A-crystallin inhibits bacterial growth.

alpha A-Crystallin and alpha Ains-crystallin are derived from the alpha A-crystallin gene via alternative splicing. They are identical except for the presence of a polypeptide, 23 amino acids long, encoded by the 'insert' exon. Evolutionary logic would suggest that the insertion of a 23 amino acid peptide in the middle of alpha A-crystallin, a protein evolving more slowly than either histone H1, cytochrome c or hemoglobin, would lead to appreciable structural and functional changes. However, based on physico-chemical studies, it is presently believed that alpha A-crystallin and alpha Ains-crystallin are functionally equivalent and that the presence of the 'insert' peptide in alpha Ains-crystallin is inconsequential. We report here that the independent expression of recombinant alpha Ains-crystallin, and not alpha A-crystallin, inhibits growth of the bacterial host. These observations were confirmed in coexpression experiments, wherein both the proteins were expressed in the same cell. Interestingly, growth inhibition is reversible. Importantly, the data demonstrate that it is catalytic amounts and not the gross accumulation of alpha Ains-crystallin which causes growth inhibition. Given the prior knowledge that alpha A-crystallin and alpha Ains-crystallin differ by a peptide of 23 amino acids, these data suggest that the "insert peptide' in alpha Ains-crystallin imparts properties on this protein that are different from alpha A-crystallin.

Animals↗
PubMed2005

Sideline management of asthma.

The timely, efficient, and effective sideline management of asthma must be based on an understanding of the disease processes, awareness of evidence-based therapeutic intervention, and thorough knowledge of the individual athlete's past and present medical history. There is accumulating evidence that exercise-induced airway narrowing, if unrecognized or inadequately treated, can progress to a severe life-threatening status and should always be viewed as a potential medical emergency. A widening range of therapeutic measures is currently available to prevent and treat exercise asthma, and treatment must be tailored to the individual circumstances in order to optimize response.

Asthma, Exercise-Induced↗
PubMed2004

Nursing process outcome linkage research: issues, current status, and health policy implications.

BACKGROUND: The use of large clinical datasets to assess the effectiveness of health care is of growing interest in continuing efforts to understand the impact of healthcare costs on quality. Correspondingly, there is a greater need to define and measure outcomes that are sensitive to nursing interventions. However, concerns exist about the ability to amass and use large clinical nursing datasets to assess the effectiveness of nursing interventions. Some nursing studies have used large clinical datasets to examine patterns of nursing diagnoses, interventions, and outcomes. Among patient populations, however, systematic effectiveness studies of nursing process and outcome linkages at the individual nurse and patient level of analysis are essentially nonexistent. This is largely the result of slow development of nursing classifications, reference terminologies, and reference information standards. Nursing information systems have an unprecedented potential for documentation of nursing practice, as well as the accumulation and analysis of large clinical datasets, to improve nursing performance, increase nursing knowledge, and provide data and information necessary for nursing to participate in the formulation of healthcare policy. OBJECTIVES: A literature search shows that a common framework is beginning to evolve that represents nursing's essential information, eg, the Nursing Minimum Data Set, Management Minimum Data Set, and several standardized nursing languages. Extensive research and other initiatives have produced 1) nursing languages and reference terminologies that span healthcare settings; 2) information models; and 3) standards for datasets supporting information systems. A number of issues remain, however, that concern the development of uniform nursing datasets, definitions of outcomes, quality of nursing data, information system design, and methods of data analysis. We review nursing process outcome research, clarify issues inherent in nursing effectiveness research, and discuss implications for nursing and health policy.

Health Policy↗
PubMed1998

Does a low nitrogen supply necessarily lead to acclimation of photosynthesis to elevated CO2?

Long-term exposure of plants to elevated partial pressures of CO2 (pCO2) often depresses photosynthetic capacity. The mechanistic basis for this photosynthetic acclimation may involve accumulation of carbohydrate and may be promoted by nutrient limitation. However, our current knowledge is inadequate for making reliable predictions concerning the onset and extent of acclimation. Many studies have sought to investigate the effects of N supply but the methodologies used generally do not allow separation of the direct effects of limited N availability from those caused by a N dilution effect due to accelerated growth at elevated pCO2. To dissociate these interactions, wheat (Triticum aestivum L.) was grown hydroponically and N was added in direct proportion to plant growth. Photosynthesis did not acclimate to elevated pCO2 even when growth was restricted by a low-N relative addition rate. Ribulose-1, 5-bisphosphate carboxylase/oxygenase activity and quantity were maintained, there was no evidence for triose phosphate limitation of photosynthesis, and tissue N content remained within the range recorded for healthy wheat plants. In contrast, wheat grown in sand culture with N supplied at a fixed concentration suffered photosynthetic acclimation at elevated pCO2 in a low-N treatment. This was accompanied by a significant reduction in the quantity of active ribulose-1, 5-bisphosphate carboxylase/oxygenase and leaf N content.

Journal Article↗
PubMed1996

Vascular occlusion in diabetic retinopathy. A qualitative and quantitative histopathological study.

The retinal vessels from seven diabetic patients and from six age-matched normal controls were studied qualitatively and quantitatively using various histological staining techniques. In diabetic patients the walls of retinal arterioles and capillaries showed significantly more staining than normals for periodic acid Schiff (neutral glycoproteins), Sirius red (connective tissue), and for Alcian blue at pH 2.6, pH 5.8 and at pH 5.8 combined with MgCl22 in concentrations less than 0.9 M (acid mucopolysaccharides). In the retina from diabetic patients there was no difference between the number of capillaries staining with these dyes in areas of vascular occlusion, and in adjacent control areas. Furthermore, in areas of vascular occlusion, the material accumulated centrally to occlude the lumen of ghost vessels did not stain with any of the dyes used. A homogenous material, accumulated in the outer retina in areas of vascular occlusion in the retina from diabetic patients, only stained with Alcian blue at pH 5.8 combined with MgCl2 in concentrations less than 0.4 M, suggesting a different molecular composition from the Alcian blue material accumulated in the retinal vascular walls. The findings are in accordance with the knowledge that basement membranes of retinal vessels are thickened in diabetes mellitus. However, the findings also indicate that basement membrane thickening cannot fully account for vascular occlusion in diabetic retinopathy.

Aged↗
PubMed1997

Heat intolerance induced by antidepressants.

A case in which prescription medications induced heat intolerance which led to heat stroke is presented. A subject who suffered from depression and was treated with fluoxetine HCL (prozac) and lithium carbonate was engaged in mild intermittent work for 4 hours under hot/dry climatic conditions (Ta = 37 degrees C, rh = 15%). The subject lost consciousness, was hyperthermic and suffered from disseminated intravascular coagulation. A year later residual cerebellar symptoms were still evident and severe atrophy of the cerebellar tissue was demonstrated in a CT scan. It is suggested that drug-induced heat intolerance was the predisposing factor that reduced the patient ability to sustain exercise-heat stress, and under the favorable environmental circumstances led to excessive heat accumulation which ultimately caused heat stroke. This is the first description, to our knowledge, of heat intolerance of a patient treated by a combination of fluoxetine and lithium carbonate.

Antidepressive Agents↗
PubMed2003

Synergistic degradation of linuron by a bacterial consortium and isolation of a single linuron-degrading variovorax strain.

The bacterial community composition of a linuron-degrading enrichment culture and the role of the individual strains in linuron degradation have been determined by a combination of methods, such as denaturing gradient gel electrophoresis of the total 16S rRNA gene pool, isolation and identification of strains, and biodegradation assays. Three strains, Variovorax sp. strain WDL1, Delftia acidovorans WDL34, and Pseudomonas sp. strain WDL5, were isolated directly from the linuron-degrading culture. In addition, subculture of this enrichment culture on potential intermediates in the degradation pathway of linuron (i.e., N,O-dimethylhydroxylamine and 3-chloroaniline) resulted in the isolation of, respectively, Hyphomicrobium sulfonivorans WDL6 and Comamonas testosteroni WDL7. Of these five strains, only Variovorax sp. strain WDL1 was able to use linuron as the sole source of C, N, and energy. WDL1 first converted linuron to 3,4-dichloroaniline (3,4-DCA), which transiently accumulated in the medium but was subsequently degraded. To the best of our knowledge, this is the first report of a strain that degrades linuron further than the aromatic intermediates. Interestingly, the rate of linuron degradation by strain WDL1 was lower than that for the consortium, but was clearly increased when WDL1 was coinoculated with each of the other four strains. D. acidovorans WDL34 and C. testosteroni WDL7 were found to be responsible for degradation of the intermediate 3,4-DCA, and H. sulfonivorans WDL6 was the only strain able to degrade N,O-dimethylhydroxylamine. The role of Pseudomonas sp. strain WDL5 needs to be further elucidated. The degradation of linuron can thus be performed by a single isolate, Variovorax sp. strain WDL1, but is stimulated by a synergistic interaction with the other strains isolated from the same linuron-degrading culture.

Betaproteobacteria↗
PubMed2003

TGF-beta signal transduction and mesangial cell fibrogenesis.

Transforming growth factor-beta (TGF-beta) is closely associated with progressive renal fibrosis. Significant progress has been accomplished in determining the cellular signaling pathways that are activated by TGF-beta. This knowledge is being applied to glomerular mesangial cell models of extracellular matrix (ECM) accumulation. A central component of TGF-beta-stimulated mesangial cell fibrogenesis is the TGF-beta family-specific Smad signal transduction pathway. However, while Smads play an important role in collagen accumulation, recent findings indicate that cross talk among a variety of pathways is necessary for maximal stimulation of collagen expression. Further investigation of these multiple interactions will provide insight into possible ways to interrupt cellular mechanisms of glomerular fibrogenesis.

Animals↗