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Biomedical subjects

C Baker

Publications and source records attributed to C Baker.

At least 55 records · Page 3Linked to original sources
PubMed1998

Risk factors for candidemia in a children's hospital.

Candida species are increasingly important nosocomial pathogens in critically ill children. A 2.3-fold increase in the rate of nosocomial candidemia at our 200-bed tertiary care children's hospital prompted a study to identify risk factors for this infection. Twenty-six cases were identified between 1992 and 1993, representing 21% of all nosocomial bloodstream infections. Candida albicans was the most frequent isolate (58%), followed by Candida parapsilosis (27%). A case-control study revealed that there was a statistically significant association between the occurrence of candidemia and placement of a central venous catheter in the femoral vein (P = .03), the use of a tunneled central venous catheter (P = .05), and prolonged hyperalimentation (P = .04). Patients with candidemia also were noted to have candiduria more often than controls (P = .003) and were more likely to have had topical antifungal agents prescribed (P = .04). Multivariate analysis showed that hyperalimentation was an independent risk factor for the development of candidemia. We conclude that measures must be taken to reduce these risk factors whenever possible.

Adolescent↗
PubMed1998

Managing organizational challenge and change: closing an inpatient unit.

The effects of a turbulent health care delivery market have impacted the day-to-day reality of acute care hospitals. One effect is that the supply of acute care hospital beds currently exceeds the demand, a trend that is expected to continue to the year 2000 and beyond. Nursing administrators at St. Marys Hospital Medical Center made the decision to close an inpatient unit in order to better match acute care bed supply to existing demand. Decision support for closure, organizational change, and lessons learned from the closure process are discussed.

Decision Making, Organizational↗
PubMed1998

Ozone alters the expression of tenascin-C in cultured primate nasal epithelial cells.

Tenascin-C is an extracellular matrix component which is transiently expressed in association with epithelial cell detachment, proliferation, and migration. This molecule has been identified in respiratory tissue, but little is known about the cellular source of tenascin-C or the factors that regulate its production. Since air pollutants are known to disrupt epithelial integrity, we investigated the regulation of tenascin-C in response to 0.3 ppm ozone in differentiated primate nasal epithelial cells in culture at an air-medium interface. The expression of tenascin-C was upregulated in response to ozone, as determined by Northern blot analysis, Western blotting, and immunofluorescent staining. In contrast, there was no change in the mRNA levels for versican, biglycan, perlecan, or collagen type I. Reduced cellular attachment to the substrate was evident in ozone-treated cultures in association with tenascin-C deposition at the interfaces between cells and basal surfaces. The presence of tenascin-C on denuded areas of the matrix suggests that tenascin-C may have been instrumental in the loss of patches of cells. The modulation of tenascin-C synthesis and distribution may play a significant role in the response of respiratory epithelial cells to ozone exposure.

Animals↗
PubMed1998

[Regional campaign promoting the use of sodium iodide: "a pinch of health"].

The regional campaign aimed at promoting consumer purchase and use of iodized salt was launched in 1988. The aim of this campaign has been to disseminate correct dietary information to regional consumers, guaranteeing at the same time the availability of iodine-enriched salt through the regional commercial distribution network. The main campaign target is to reach average consumption levels in the more developed countries. The regional campaign is a part of the world-wide WHO and UNICEF projects aimed at eradicating thyroid disorders due to an inadequate iodine intake. The campaign is to be further developed through health and consumer education programs in the school as well as a wider coverage of the issue in the mass-media.

Advertising↗
PubMed1998

Music as an adjunct to antiemetic therapy.

PURPOSE/OBJECTIVES: To test whether use of music as a diversional intervention during high-dose chemotherapy administration would affect perception of nausea and episodes of vomiting. SAMPLE: 39 patients undergoing bone marrow transplant. A total of 33 patients were included in the data analysis, with 17 in the control group and 16 in the music intervention group. METHODS: Patients were assigned randomly to a control group (usual antiemetic protocol) or the experimental group (usual antiemetic group plus music intervention during the 48 hours of high-dose cyclophosphamide administered as part of the preparative regimen). MAIN RESEARCH VARIABLES: Use of a music intervention, perception of nausea, and instances of vomiting. FINDINGS: Significant differences were found between group scores on a visual analog scale for nausea and number of episodes of vomiting, demonstrating that the experimental group experienced less nausea and fewer instances of vomiting. CONCLUSION: This study found that music is an effective adjunct to a pharmacologic antiemetic regimen for lessening nausea and vomiting, and this study merits further investigation through a larger multi-institutional effort. IMPLICATIONS FOR NURSING PRACTICE: Using music as a diversional adjunct intervention to antiemetic therapy is helpful in decreasing nausea and vomiting. The intervention can be initiated independently by nurses and individualized for each patient, leading to greater patient comfort and compliance with high-dose chemotherapy.

Antineoplastic Agents, Alkylating↗
PubMed1997

Two naturally occurring insulin receptor tyrosine kinase domain mutants provide evidence that phosphoinositide 3-kinase activation alone is not sufficient for the mediation of insulin's metabolic and mitogenic effects.

We have recently reported (1) that two naturally occurring mutants of the insulin receptor tyrosine kinase domain, Arg-1174 --> Gln and Pro-1178 --> Leu (Gln-1174 and Leu1178, respectively), both found in patients with inherited severe insulin resistance, markedly impaired receptor tyrosine autophosphorylation, with both mutant receptors being unable to mediate the stimulation of glycogen synthesis or mitogenesis by insulin when expressed in Chinese hamster ovary cells. However, these mutations did not fully prevent IRS-1 phosphorylation in response to insulin in these cells, suggesting that IRS-1 alone may not be sufficient to mediate insulin's metabolic and mitogenic effects. In the present study, we have demonstrated that these mutations also impair the ability of the insulin receptor to activate the transcription factor Elk-1 and promote GLUT4 translocation to the plasma membrane. Although at low concentrations of insulin, the mutant receptors were impaired in their ability to stimulate the tyrosine phosphorylation of IRS-1, at higher insulin concentrations we confirmed that the cells expressing the mutant receptors showed significantly increased tyrosine phosphorylation of IRS-1 compared with parental nontransfected cells. In addition, at comparable insulin concentrations, the association of the p85alpha subunit of phosphoinositide 3-kinase (PI3-kinase) with IRS-1 and the enzymatic activity of IRS-1-associated PI3-kinase were significantly enhanced in cells expressing the mutant receptors. In contrast, no significant stimulation of the tyrosine phosphorylation of Shc, GTP loading of Ras, or mitogen-activated protein kinase phosphorylation was seen in cell lines expressing these mutant receptors. Thus, no activation of any measurable mitogenic or metabolic response was detectable, despite significant insulin-induced phosphorylation of IRS-1 and its association with PI3-kinase in cells stably expressing the mutant insulin receptors. These findings suggest that PI3-kinase activation alone may be insufficient to mediate a wide range of the metabolic and mitogenic effects of insulin. Additionally, the data provide support for the notion that insulin activation of Ras is more closely linked with Shc, and not IRS-1, phosphorylation.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Crystalluria and urinary tract abnormalities associated with indinavir.

BACKGROUND: Indinavir, a protease inhibitor widely used to treat patients with HIV infection, has been associated with nephrolithiasis. Distinctive urinary crystals and a spectrum of urologic disorders were noted in patients receiving indinavir. OBJECTIVE: To determine the composition of urinary crystals and the frequency of asymptomatic crystalluria and urinary tract symptoms in patients receiving indinavir. PATIENTS: Patients with HIV infection who were enrolled in studies conducted at the National Institutes of Health. MEASUREMENTS: Microscopic urinalysis, high-performance liquid chromatography (HPLC) and mass spectrometry of urinary crystals and stones, and clinical evaluation of patients with urologic symptoms. RESULTS: Of 240 patients receiving indinavir, 142 provided urine specimens for analysis. Twenty-nine (20%) had crystals consisting of plate-like rectangles and fan-shaped or starburst forms. Mass spectrometry and HPLC confirmed that these crystals were composed of indinavir. Of 40 patients who were not receiving indinavir, none had similar crystals (P < 0.001). Nineteen of the 240 patients receiving indinavir (8%) developed urologic symptoms. Of these, 7 (3%) had nephrolithiasis and the other 12 (5%) had previously undescribed syndromes: crystalluria associated with dysuria and crystalluria associated with back or flank pain. Four of the patients with the latter syndrome had radiographic evidence of intrarenal sludging. CONCLUSIONS: Indinavir forms characteristic crystals in the urine. This crystalluria may be associated with dysuria and urinary frequency, with flank or back pain associated with intrarenal sludging, and with the classic syndrome of renal colic.

Adult↗
PubMed1997

Release of RANTES from nasal and bronchial epithelial cells.

RANTES is a chemokine with eosinophil attractant and activating activities. This study was undertaken to determine whether primary cultures of human nasal and primate bronchial epithelial cells produce RANTES and the effect of various cytokines and dexamethasone on the release of this chemokine. Nasal epithelial cells from 32 patients (HNE) and bronchial epithelial cells from 17 Macaca nemestrina monkeys (PBE) were cultured in vitro for 24 to 72 h with LPS, TNF-alpha, IL-1 beta, IFN-gamma and TNF-alpha combined with IFN-gamma and/or dexamethasone at 10 to 1000 micrograms/ml. Culture supernatants were assayed for RANTES by ELISA. RANTES synthesis was measured by immunoprecipitation. HNE and PBE released modest constitutive amounts of RANTES (350 to 1000 pg/ml) which did not increase with time in culture. Release of RANTES was stimulated by all activators except LPS in a time-dependent manner, with the greatest synthesis induced by the combined addition of TNF-alpha and IFN-gamma. The combination of these activators also increased RANTES synthesis as determined by immunoprecipitation. Dexamethasone at 100 and 1000 micrograms/ml produced significant inhibition of stimulated RANTES release. These data indicate that normal nasal and bronchial epithelial cells release RANTES which is upregulated by various cytokines and inhibited by dexamethasone. The enhanced release is due to stimulation of both synthesis and secretion. Production of RANTES by epithelial cells could contribute to the inflammation that characterizes the respiratory tract in asthma and rhinitis and downregulation of RANTES by glucocorticoids may be one mechanism of the therapeutic effect of these agents.

Adult↗
PubMed1997

Cultural relativism and cultural diversity: implications for nursing practice.

This article examines the doctrine of cultural relativism in nursing practice. To introduce the issue, an overview of the intellectual history of cultural relativism is presented. The academic themes of the debate surrounding cultural relativism are illustrated with an example of the social controversy in France involving cultural relativism as used to defend the practice of female genital excision among immigrant communities. The dilemma faced by nursing in making cross-cultural judgments is then examined in the light of the academic and social debates. The article concludes with a theoretical resolution of the issue of cultural relativism for nursing practice that is based on hermeneutic philosophy.

Africa↗
PubMed1997

High affinity binding of pyrethroids to the alpha subunit of brain sodium channels.

Na+ channels are the primary molecular targets of the pyrethroid insecticides. Na+ channels consisting of only a type IIA alpha subunit expressed in Chinese hamster ovary cells responded to pyrethroid treatment in a normal manner: a sustained Na+ current was induced progressively after each depolarizing pulse in a train of stimuli, and this Na+ current decayed slowly on repolarization. These modified Na+ channels could be reactivated at much more negative membrane potentials (V0.5 = -139 mV) than unmodified Na+ channels (V0.5 = -28 mV). These results indicate that pyrethroids can modify the functional properties of the Na+ channel alpha subunit expressed alone by blocking their inactivation, shifting their voltage dependence of activation, and slowing their deactivation. To demonstrate directly the specific interaction of pyrethroids with the alpha subunit of voltage-gated Na+ channels, a radioactive photosensitive derivative, [3H]RU58487, was used in binding and photolabeling studies. In the presence of a low concentration of the nonionic detergent Triton X-100, specific pyrethroid binding to Na+ channels in rat brain membrane preparations could be measured and reached 75% of total binding under optimal conditions. Binding approached equilibrium within 1 hr at 4 degrees, dissociated with a half-time of approximately 10 min, and had K(D) values of approximately 58-300 nM for three representative pyrethroids. Specific pyrethroid binding was enhanced by approximately 40% in the presence of 100 nM alpha-scorpion toxin, but no allosteric enhancement was observed in the presence of toxins acting at other Na+ channel receptor sites. Extensive membrane washing increased specific binding to 89%. Photolabeling with [3H]RU58487 under these optimal binding conditions revealed a radiolabeled band with an apparent molecular mass of 240 kDa corresponding to the Na+ channel alpha subunit. Anti-peptide antibodies recognizing sequences within the alpha subunit were able to specifically immunoprecipitate the covalently modified channel. Together, these results demonstrate that the pyrethroids can modify the properties of cells expressing only the alpha subunit of Na+ channels and can bind specifically to a receptor site on the alpha subunit.

Amino Acid Sequence↗
PubMed1997

Adolescent TMJ tomography and magnetic resonance imaging: a comparative analysis.

The predictive value of radiographic tomography was assessed using magnetic resonance imaging as a definitive test of TMJ soft-tissue status in a predominantly asymptomatic adolescent sample. Eighty-two TMJs in 41 subjects (mean age = 12.5 years, range = 10 to 17 years) were independently evaluated using axially corrected tomography and magnetic resonance imaging. Tests of comparison and correlation were performed. Correspondence of tomographic classification to magnetic resonance imaging classification of nondisplacement (55%), reducing internal derangement (35%), or nonreducing internal derangement (10%) showed a significant relationship (P < .05). Tomography as a diagnostic test of abnormal disc position had a sensitivity of 0.43, a specificity of 0.80, a positive predictive value of 0.64, and a negative predictive value of 0.63. Tomography is inappropriate as a diagnostic test for TMJ internal derangement.

Adolescent↗
PubMed1996

Inhibition of neurotransmission by peptides containing the synaptic protein interaction site of N-type Ca2+ channels.

N-type Ca2+ channels bind directly to the synaptic core complex of VAMP/synaptobrevin, syntaxin, and SNAP-25. Peptides containing the synaptic protein interaction ("synprint") site caused dissociation of N-type Ca2+ channels from the synaptic core complex. Introduction of synprint peptides into presynaptic superior cervical ganglion neurons reversibly inhibited synaptic transmission. Fast EPSPs due to synchronous transmitter release were inhibited, while late EPSPs arising from asynchronous release following a train of action potentials were increased and paired-pulse facilitation was increased. The corresponding peptides from L-type Ca2+ channels had no effect, and the N-type peptides had no effect on Ca2+ currents through N-type Ca2+ channels. These results are consistent with the hypothesis that binding of the synaptic core complex to presynaptic N-type Ca2+ channels is required for Ca2+ influx to elicit rapid, synchronous neurotransmitter release.

Animals↗
PubMed1996

An investigation into the attitudes and practices of intensive care nurses towards verbal communication with unconscious patients.

This study attempted to investigate the attitudes and practices of intensive care nurses towards verbal communication with unconscious patients. A sample of five staff nurses working in an intensive care unit in Northern Ireland formed the basis for the study. The research design was non-experimental and descriptive-exploratory in nature, incorporating 4-hourly observational periods and structured interviews. Qualitative and quantitative analysis indicated that intensive care nurses spend on average 5% of their time verbally communicating with unconscious patients. Most of this communication involves informing the patient of immediate procedural matters or providing reassuring statements. Most intensive care nurses claim that verbal communication with unconscious patients is very important, and some ambiguity is apparent as to the unconscious patient's level of awareness. Major factors influencing communication are the patient's level of consciousness, the amount of physical care being given and the presence of relatives.

Coma↗
PubMed1996

An amino-terminal truncated progesterone receptor isoform, PRc, enhances progestin-induced transcriptional activity.

Previously we reported the identification of two unique progesterone receptor (PR) messenger RNA transcripts that encode a smaller PR isoform, termed the C-receptor (PRc). These two PR transcripts encode a protein that is N-terminally truncated, so that it lacks the first zinc finger of the DNA binding domain, but still contains a complete hormone binding region with sequences for dimerization and nuclear localization. We also have demonstrated the existence of a 60-kDa progestin-specific binding protein in progestin target cells using a monoclonal antibody directed to the C-terminus of PRs, suggesting that these two novel transcripts generate a truncated form of PR. In this paper, we address the hypothesis that the C-receptor arises from the initiation of translation of a methionine C-terminal to the methionine start sites that generate the larger 94-kDa A and 116-kDa B human PR isoforms. The studies shown here support the postulate that another downstream in-frame methionine within the PR-coding region can serve as a translation initiation site for the generation of a third PR protein. A partial PR complementary DNA, lacking the translation start sites for B- and A-receptors was translated in vitro. The synthetic protein product bound [3H]progestins and unlabeled progestins. The antiprogestin RU486 also competed for this binding. Transfection of this partial PR complementary DNA into PR-negative HeLa cells resulted in progestin-specific binding activity. Because the third PR isoform lacks the first zinc finger of the DNA binding domain, but contains sequences for dimerization, we reasoned that the C-receptor isoform would be transcriptionally in-active and not bind DNA directly. Surprisingly, however, in the presence of A- and/or B-receptors, we found that C-receptors can modulate the transcriptional activity of A- and/or B-receptors using a reporter gene. These studies emphasize that multiple receptor isoforms may have distinct biological properties, and that the truncated C-receptor may play a role in explaining some of the pleiotropic effects of progestins.

Antineoplastic Agents↗
PubMed1996

Subjective experience of symptoms in schizophrenia.

A qualitative study using the interpretive interactionism method was conducted to investigate the inner experiences of individuals with schizophrenia that surround, mobilize, and shape their awareness of, and responses to, the symptoms of their illness. Biographical data were collected from a purposive sample of 15 respondents suffering from this illness. Their narratives indicated that psychic pain dominated their lives; this theme was intertwined with the themes of lack of control, failure, and loss. Psychic pain was the key factor in informants' developing recognition of fluctuations in the course of their illness. The findings suggest that nurses may facilitate symptom monitoring in individuals who have schizophrenia, by attending to the emotional distress permeating every facet of their existence and by helping them look inward, to heighten their consciousness of specific components of psychic distress.

Adaptation, Psychological↗
PubMed1996

The surface morphology of the omasum of the African goat.

The microstructure of the omasum of the African goat was investigated macroscopically, as well as by scanning electron microscopy to determine how the omasum is anatomically specialised to enable the goat to graze and browse so successfully in the harsh environments of Africa. The omasum of the African goat was found to be more simple in structure than that of other domesticated ruminants. The omasal laminae were arranged in only 3 orders with the number of laminae varying between 27 and 33, considerably fewer than previously described for other goats, sheep or cattle. The large conical and unguiculiform papillae surrounding the reticulo-omasal orifice, as well as the hooked papillae present on the laminae, were more similar to those of wild ruminants that browsed than domestic grazing species. The papillae on the laminae were also found to be directionally orientated towards the orifices, which may suggest a "sieve mechanism' at the reticulo-omasal orifice and interlaminar spaces. In addition, it may suggest a directional movement of ingesta between the laminae. The stratified squamous epithelium lining the laminae and papillae was lightly keratinised which, along with the microplicae-like surface folds and pits of the superficial cells, indicated that it was functionally structured for absorption. These morphological specialisations of the omasal surfaces of the indigenous African goat demonstrated similarities with that of wild ruminants that are able to graze and browse.

Animals↗