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Biomedical subjects

M Gustafson

Publications and source records attributed to M Gustafson.

At least 19 recordsLinked to original sources
PubMed2001

The effects of readers' goals on inference generation and memory for texts.

We investigated the effects of readers' goals on inference generation and memory for expository text. College students (N = 82) read texts for the purpose of either study or entertainment. On-line inference generation was recorded via think-aloud procedures, and off-line memory was assessed via free recall. Reading goal strongly influenced inferential activity: Readers with a study goal produced more coherence-building (i.e., backward/explanatory and forward/predictive) inferences, whereas readers with an entertainment goal produced more associations and evaluations. These differences were associated with superior memory for the texts in the study condition. The results indicate that inference generation during reading is partly strategic and is influenced systematically by reading purpose. We propose that reading goals influence readers' standards of coherence, which in turn influence the types of inferences that they draw and the final memory representations that they construct.

Adult↗
PubMed2000

Tracheal reconstruction using alcohol-stored homologous cartilage and autologous cartilage in the rabbit model.

OBJECTIVE: Reconstruction of laryngotracheal stenosis continues to pose a significant challenge. Cartilage grafts have been in use for almost a century, but despite good clinical results, many questions concerning the survival and growth of implanted cartilage persist. To reduce donor site morbidity, the use of homologous cartilage has been investigated. This study compared alcohol-stored homologous auricular cartilage with autologous auricular cartilage for anterior graft laryngotracheal reconstruction in a rabbit model. METHODS: Autologous and alcohol preserved homologous auricular cartilage was transplanted to the resected anterior tracheal wall of the twenty New Zealand rabbits. Rabbits were sacrificed 6 weeks after surgery and histologic analysis was performed on the implanted cartilage grafts. RESULTS: The autografts were significantly more likely than the homografts to demonstrate viable cells (95% vs. 30%, P<0.05) and less likely to exhibit significant resorption, fibrosis or necrosis (P<0.05). Resorption and necrosis were most common in areas of trauma to the graft. Complete epithelialization occurred in all of the autografts but in only 65% of the homografts (P<0.05). New cartilage formation and integration of the implanted grafts was poor with both types of grafts. CONCLUSION: Autologous cartilage appears to have better survival than alcohol preserved homologous cartilage when used for anterior graft laryngotracheal reconstruction in a rabbit model.

Animals↗
PubMed2000

Survivors of catastrophic illness: outcome after direct transfer from intensive care to extended care facilities.

OBJECTIVE: To describe outcomes of adult survivors of prolonged critical illness after direct transfer to extended care facilities. DESIGN: A retrospective cohort study. SETTING: All adult intensive care units (ICUs) in a tertiary care university hospital. PATIENTS: A consecutive series of 97 adult survivors with an ICU stay of > or =7 days transferred directly from intensive care to extended care facilities between 1990 and 1996. INTERVENTIONS: None. METHODS AND MAIN RESULTS: Hospital and extended care facility charts were reviewed for patient characteristics, resource utilization, and survival. Survivors were for a minimum of 1 yr and a maximum of 6 yrs, and were interviewed to assess quality of life and functionality. The mean age of the patients was 66+/-16 (range, 19-93) yrs. The median length of ICU stay for these patients was 39 (range, 7-276) days. Only 18 of the 71 ventilator-assisted patients were weaned from mechanical ventilation after transfer to the extended care facility. Survival for the study period, at 1 yr after discharge from the ICU, was 49.5%. One year after discharge from the ICU, 11.5% of all patients had returned home, were breathing spontaneously, had a fair or better quality of life, and had good physical functionality. Each successive year, an increasing proportion of patients underwent direct transfer to an extended care facility. This strategy decreased the patients' length of stay (p<.002) in the ICU from year to year, but was significantly associated with an increase in readmissions to acute care hospitals (p<.002). CONCLUSIONS: Survivors of catastrophic illness who are so debilitated that they require transfer to an extended care facility have a low likelihood of achieving both survival and functional independence 1 yr after discharge from the ICU. Aggressive cost-conscious strategies to accelerate the transfer of these patients successfully reduced the length of ICU stay and hospital costs, but were associated with a high rate of readmission to tertiary care facilities.

Adult↗
PubMed1999

Blood safety. The Food and Drug Administration's role.

The federal government has a role in protecting consumers from threats to the blood supply. These threats range from the residual risks of known infection, to emerging infections that may contaminate the blood supply, to complacency in the area of adherence to product standards and Current Good Manufacturing Practices. The Food and Drug Administration is tasked with oversight of the safety of the nation's blood supply. The Food and Drug Administration's regulation of blood and blood components includes preapproval for products entering interstate commerce and adherence to Current Good Manufacturing Practices for all blood components. Oversight for Current Good Manufacturing Practices compliance includes inspection and reporting requirements. These regulatory programs are coupled with the Public Health Service's ongoing research and epidemiological surveillance. The goals of these programs are to prevent another infectious disease epidemic from infecting the blood supply as did the acquired immunodeficiency syndrome in the early 1980s and to further improve blood safety.

Blood Transfusion↗
PubMed1997

Toxicity of white phosphorus to waterfowl: acute exposure in mallards.

As part of an effort to understand extensive, white phosphorus (P4)-induced waterfowl mortality at Eagle River Flats, Fort Richardson, Alaska (USA), we conducted a number of acute toxicity tests using penned mallards (Anas platyrhynchos) in 1993 and 1994. The 24-hr median lethal dose (LD50) for P4 dissolved in oil was 6.46 mg/kg in adult males and 6.96 mg/kg in adult females. Although the median lethal doses were not statistically different, the female dose-response curve had a statistically shallower slope than that of males. The LD50 for the ecologically more relevant pelletized form of P4 in adult males was 4.05 mg/kg. In mallards, one mechanism of P4 toxicity caused rapid (3 to 10 hr) mortality and had signs consistent with anoxia. A second, slower acting mechanism resulted in hepatic and renal pathology including extensive fat deposition in the liver and cellular necrosis. White phosphorus accumulated in adipose tissues, but only for a few days.

Adipose Tissue↗
PubMed1995

Neuroendocrine profile of the potential anxiolytic drug S-20499.

The neuroendocrine profile of the serotonin 5-HT1A receptor agonist and potential anxiolytic drug (+)-4[N-(5-methoxy-chroman-3-yl)N-propylamino]butyl-8-azaspiro-(4, 5)-decane - 7,9-dione (S-20499) was examined in conscious male rats. S-20499 (0.01-20 mg/kg i.p.) dose-dependently elevated plasma adrenocorticotropin (ACTH) and corticosterone concentrations, with maximal effects observed at 15-30 and 30-60 min respectively. S-20499 also reduced plasma prolactin concentration, and did not alter plasma renin activity. S-20499 (1 mg/kg i.p.) also reduced blood pressure and heart rate within 10 min, suggesting reduced sympathetic output. Pretreatment with the 5-HT1A receptor antagonists (-)-pindolol (0.3 mg/kg i.p.) or spiperone (0.01 or 3 mg/kg s.c.) significantly attenuated the stimulatory effects of S-20499 on plasma ACTH and/or corticosterone concentrations. The data suggest that S-20499 stimulates the hypothalamic-pituitary adrenal axis by activating 5-HT1A receptors, although activation of dopamine D2 receptors may contribute to these responses. Like other 5-HT1A receptor agonists, S-20499 does not increase renin secretion. Additionally, it reduces prolactin secretion, presumably by acting as a weak dopamine D2 receptor agonist in the pituitary.

Adrenocorticotropic Hormone↗
PubMed1993

Prosthetic valve endocarditis resulting from nosocomial bacteremia. A prospective, multicenter study.

OBJECTIVE: To determine the incidence of endocarditis in bacteremic patients with prosthetic heart valves and the risk factors for and the effect of duration of antibiotic therapy on development of endocarditis in such patients. DESIGN: Multicenter, prospective observational study. SETTING: Six university teaching hospitals with high-volume cardiothoracic surgery. PARTICIPANTS: One hundred seventy-one consecutive patients with prosthetic heart valves who developed bacteremia during hospitalization. MEASUREMENTS AND MAIN RESULTS: Patients were evaluated when they were identified as having bacteremia and 1, 2, 6, and 12 months after its occurrence. Of 171 patients, 74 (43%) developed endocarditis: Fifty-six (33%) had prosthetic valve endocarditis at the time bacteremia was discovered ("endocarditis at outset"), whereas 18 (11%) developed endocarditis a mean of 45 days after bacteremia was discovered ("new endocarditis"). Mitral valve location and staphylococcal bacteremia (Staphylococcus aureus or S. epidermidis) were significantly associated with the development of "new" endocarditis. All 18 cases of new endocarditis were nosocomial, and in 6 of these cases (33%) bacteremia was acquired via intravascular devices. Twenty-one patients without evidence of endocarditis at the time of bacteremia received short-term antibiotic therapy (< 14 days); 1 patient (5%) developed endocarditis. Eleven of 70 patients (16%) who received long-term antibiotic therapy (> 14 days) developed endocarditis (P > 0.2). CONCLUSIONS: Bacteremic patients with prosthetic heart valves were at notable risk for developing endocarditis, even when they received antibiotic therapy before endocarditis developed and regardless of the duration of such therapy. Intravascular devices were a common portal of entry.

Adult↗
PubMed1993

Actin dynamics in human neutrophils during adhesion and phagocytosis is controlled by changes in intracellular free calcium.

The role of changes in cytosolic free calcium concentration ([Ca2+]i) in the assembly and disassembly of actin during adhesion and phagocytosis was evaluated. Rhodamine-phalloidin staining combined with quantitative fluorescence and confocal laser scanning microscopy was used to measure local F-actin changes in single adherent human neutrophils phagocytosing yeast particles on different surfaces and under different calcium conditions. Cells were suspended in a) calcium-containing medium (CCM) or b) calcium-free medium (CFM) or c) were first depleted of calcium (i.e., MAPT/AM-loaded in CFM) and then suspended in CFM (MAPT). In parallel, local [Ca2+]i changes were monitored using a fura-2 ratio imaging system. In CCM or CFM, attachment to the substrate and formation of pseudopods around a yeast particle generated, within a few seconds, rises in [Ca2+]i, both around the phagosome and in the cell body. During continued phagocytosis, [Ca2+]i was more elevated around the phagosome compared to the rest of the cell. No [Ca2+]i fluctuations were observed in MAPT cells. Adhesion and phagocytosis led to a several-fold increase in F-actin. The increase was transient in cells in CCM and CFM, but remained high in Ca-depleted neutrophils. A distinct ring of F-actin was formed around a phagosome with a yeast particle. Twenty min after ingestion the amount of this actin decreased more than 50% in CCM and CFM cells but increased by 40 to 100% in MAPT cells. The accumulation of F-actin in MAPT cells was reduced to resting levels by adding Ca2+ and ionomycin after ingestion. This treatment reestablished the periphagosomal [Ca2+]i rises, as observed in CCM cells. In conclusion, the present study shows that the actin polymerization, occurring in human neutrophils during adhesion and phagocytosis, is not influenced by changes in [Ca2+]i, whereas the subsequent depolymerization is. The accumulation of actin filaments around the phagosome in calcium-depleted cells could be involved in the inhibition of phagolysosome fusion seen in the absence of [Ca2+]i changes (Jaconi et al., J. Cell Biol. 110, 1555-1564 (1990)). This suggests that the actin network, controlled by [Ca2+]i, regulates the movement of granules during phagocytosis.

Actins↗
PubMed1992

A novel principle for quantitation of fast intracellular calcium changes using Fura-2 and a modified image processing system--applications in studies of neutrophil motility and phagocytosis.

A new principle is described for imaging intracellular free calcium [Ca2+]i changes in single, living cells utilizing the fluorescent probe Fura-2. It is based upon video color mixing in real time and allows high-speed visualization, at maximum image resolution, of [Ca2+]i changes without digital image ratioing. The epifluorescence images produced by 340 and 380 nm excitations are stored in two memory buffers of a personal computer-based image processing system. Two video signals are generated independently from each buffer and connected to the red and green inputs of a video display. An image is this way created, in which [Ca2+]i shows up as a specific hue, whereas changes in dye concentration, light intensity, cell thickness show up as variations in brightness of the imaged cells. The method has advantages over conventional ratio imaging, notably simplicity and speed, since no calculations are made. Yet it can be combined with traditional digital image processing. The imaging technique allows monitoring of [Ca2+]i changes in rapidly moving cells, like neutrophils. It is demonstrated that during random locomotion on serum-coated glass surfaces, [Ca2+]i levels appeared to oscillate and that the frequency of the oscillations are related to locomotive activity. Furthermore, in Ca2+ free medium, the cells continue to move and phagocytose in the presence of Ca2+ ionophore (ionomycin) and 2 mM EGTA. In the presence of 1 mM extracellular Ca2+, ionomycin-treated cells were not able to move or phagocytose.

Calcium↗
PubMed1988

Pulse oximetry during extradural analgesia for extracorporeal shock wave lithotripsy.

Exracorporeal shock wave lithotripsy (ESWL) may require immersion of the patient in water and extradural blockade for analgesia, which may both affect pulmonary and cardiovascular function and increase the likelihood of hypoxaemia. Twenty-four patients (ASA I-III) with extradural blockade and six healthy subjects were studied by pulse oximetry during immersion. Oxygen saturation (SaO2) tended to decrease after induction of extradural analgesia. Immersion decreased SaO2 further, by up to 2% in healthy volunteers (P less than 0.05) and 3% in patients (P less than 0.05). In two patients with arteriosclerosis, an SaO2 of 92% was accompanied by arrhythmias which resolved after administration of oxygen.

Adult↗
PubMed1975

Metabolism of N-carbobenzoxyl-L-tryptophan by Chromobacterium violaceum.

Chromobacterium violaceum (ATCC 12472) metabolizes N-carbobenzoxyl-L-tryptophan into its 2', 3'-dehydro-derivative, and indole-3-propionic acid into indole-3-acrylic acid. The biotransformation accurs in resting cell incubations, and in growing cultures of the bacterium. Tryptophan in fermentation media enhances the ability of Chromobacterium violaceum to perform the conversion by an undetermined mechanism. The amino acid also prevents stored cultures from losing the ability to accomplish the biotransformation. The reaction apparently requires oxygen, and preliminary experiments suggest that it is catalyzed by a dehydrogenase.

Acrylates↗