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Biomedical subjects

S Peterson

Publications and source records attributed to S Peterson.

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

Improving care for adults with asthma across the continuum.

Asthma affects approximately 14.6 million people in the United States. Despite the publication of multiple guidelines, the delivery of care has not substantially changed. This article describes a program at Advocate Health Care to improve the delivery of care to adults with asthma in a variety of settings. Using standard patient education materials and a variety of continuous quality improvement tools, this project enhances partnership between patients and health care providers.

Adult↗
PubMed1998

Do the magnocellular and parvocellular visual pathways contribute differentially to subitizing and counting?

We investigated the neurobiological basis of visual processes involved in object enumeration. Subitizing, the ability to rapidly and accurately enumerate four or fewer objects, is thought to depend on preattentive processing of visual stimuli, whereas counting of more numerous objects is thought to require serial shifts of attention. We attempted to distinguish between the hypothesis that the magnocellular (M) visual pathway is the preferential route for subitizing, and the alternative hypothesis that there is no selectivity for the M pathway or its counterpart, the parvocellular (P) visual pathway, in visual object enumeration. Green rectangles were presented on an equiluminant red background to impair M pathway processing. This slowed enumeration performance relative to a control condition in which object/background luminance differed, especially when the rectangles were relatively large and widely spaced and had constant retinal eccentricity. When low luminance contrast was used to impair processing along the P pathway, enumeration performance was slowed relative to a high-contrast control condition, especially when the rectangles were small and closely spaced. Overall, our manipulations affected enumeration performance without selectivity for subitizing or counting ranges and without altering the slope of the functions relating reaction time to numerosity. Thus, our results favor the hypothesis that visual enumeration does not depend preferentially on either the M or the P pathway.

Humans↗
PubMed1998

Justification for visceral angiography prior to pancreaticoduodenectomy.

The hepatic arterial anatomy is aberrant in almost 50 per cent of all individuals. The most common anomalies include the right hepatic artery arising from the superior mesenteric artery (25%) and the left hepatic artery arising from the left gastric artery (25%). Anomalies of the common hepatic artery, usually a branch of the celiac artery, are rare. A replaced common hepatic artery originating from the superior mesenteric artery occurs in 2.5% of the entire population. Injury to hepatic blood supply is more common in the presence of aberrant arterial anatomy. Knowledge of aberrant arterial anatomy in patients about to undergo pancreaticoduodenectomy can lead to measures to preserve the vessels, and avoid fatal hepatic injury. We present a patient with a replaced common hepatic artery originating from the superior mesenteric artery successfully treated with a standard pancreaticoduodenectomy for pancreatic adenocarcinoma. The anomalous vessel was identified on visceral angiography, performed as part of the initial preoperative evaluation. At the time of laparotomy, the artery followed a course atypical for replaced hepatic arteries, lying medial to the common bile duct, and closely mimicking the gastroduodenal artery that would normally be divided during a Whipple procedure. This case emphasizes the importance of preoperative visceral angiography and the margin of safety it can provide when that knowledge is used in the operative strategy. Visceral angiography should be considered routine before pancreaticoduodenectomy, particularly in surgical residency training programs.

Hepatic Artery↗
PubMed1998

Substance use and social outcomes among participants in perinatal alcohol and drug treatment.

In recent years comprehensive, woman-centered alcohol and other drug (AOD) treatment programs for pregnant and parenting women have increased in number, despite a scarcity of information about their effectiveness. In response, an evaluation study was undertaken to document the behavioral and social outcome among a sample of women enrolled in AOD treatment through a California network of perinatal treatment services. A sample of 591 women were interviewed shortly before leaving treatment about their pretreatment and current treatment experiences, and 460 of them completed a follow-up interview 6 months later. Areas of positive change observed included reductions in AOD use, maintenance of some kind of treatment contact after discharge from the perinatal treatment program, reductions in criminal activity, and reductions in social problems. These findings suggest that comprehensive programs are effective at promoting recovery and positive social changes for pregnant and parenting women and their children.

Adolescent↗
PubMed1997

The complete genome sequence of the hyperthermophilic, sulphate-reducing archaeon Archaeoglobus fulgidus.

Archaeoglobus fulgidus is the first sulphur-metabolizing organism to have its genome sequence determined. Its genome of 2,178,400 base pairs contains 2,436 open reading frames (ORFs). The information processing systems and the biosynthetic pathways for essential components (nucleotides, amino acids and cofactors) have extensive correlation with their counterparts in the archaeon Methanococcus jannaschii. The genomes of these two Archaea indicate dramatic differences in the way these organisms sense their environment, perform regulatory and transport functions, and gain energy. In contrast to M. jannaschii, A. fulgidus has fewer restriction-modification systems, and none of its genes appears to contain inteins. A quarter (651 ORFs) of the A. fulgidus genome encodes functionally uncharacterized yet conserved proteins, two-thirds of which are shared with M. jannaschii (428 ORFs). Another quarter of the genome encodes new proteins indicating substantial archaeal gene diversity.

Archaeoglobus fulgidus↗
PubMed1997

An oscillating manganese electron paramagnetic resonance signal from the S0 state of the oxygen evolving complex in photosystem II.

Photosynthesis produces the oxygen necessary for all aerobic life. During this process, the manganese-containing oxygen evolving complex (OEC) in photosystem II (PSII), cycles through five oxidation states, S0-S4. One of these, S2, is known to be paramagnetic and gives rise to electron paramagnetic resonance (EPR) signals used to probe the catalytic structure and function of the OEC. The S0 states has long been thought to be paramagnetic. We report here a Mn EPR signal from the previously EPR invisible S0 state. The new signal oscillates with a period of four, indicating that it originates from fully active PSII centers. Although similar to the S2 state multiline signal, the new signal is wider (2200 gauss compared with 1850 gauss in samples produced by flashing), with different peak intensity and separation (82 gauss compared with 89 gauss). These characteristics are consistent with the S0 state EPR signal arising from a coupled MnII-MnIII intermediate. The new signal is more stable than the S2 state signal and its decay in tens of minutes is indicative of it originating from the S0 state. The S0 state signal will provide invaluable information toward the understanding of oxygen evolution in plants.

Electron Spin Resonance Spectroscopy↗
PubMed1997

Inappropriate hospital use by patients receiving care for medical conditions: targeting utilization review.

OBJECTIVE: To describe characteristics associated with inappropriate hospital use by patients in Manitoba in order to help target concurrent utilization review. Utilization review was developed to reduce inappropriate hospital use but can be a very resource-intensive process. DESIGN: Retrospective chart review of a sample of adult patients who received care for medical conditions in a sample of Manitoba hospitals during the fiscal year 1993-94; assessment of patients at admission and for each day of stay with the use of a standardized set of objective, nondiagnosis-based criteria (InterQual). PATIENTS: A total of 3904 patients receiving care at 26 hospitals. OUTCOME MEASURES: Acute (appropriate) and nonacute (inappropriate) admissions and days of stay for adult patients receiving care for medical conditions. RESULTS: After 1 week, 53.2% of patients assessed as needing acute care at admission no longer required acute care. Patients 75 years of age or older consumed more than 50% of the days of stay, and 74.8% of these days of stay were inappropriate. Four diagnostic categories accounted for almost 60% of admissions and days, and more than 50% of those days of stay were inappropriate. Patients admitted through the emergency department were more likely to require acute care (60.9%) than others (41.7%). Patients who were Treaty Indians had a higher proportion of days of stay requiring acute care than others (45.9% v. 32.8%). Patients' income and day of the week on admission (weekday v. weekend) were not predictive factors of inappropriate use. CONCLUSION: Rather than conducting a utilization review for every patient, hospitals might garner more information by targeting patients receiving care for medical conditions with stays longer than 1 week, patients with nervous system, circulatory, respiratory or digestive diagnoses, elderly patients and patients not admitted through the emergency department.

Adolescent↗
PubMed1997

The complete genome sequence of the gastric pathogen Helicobacter pylori.

Helicobacter pylori, strain 26695, has a circular genome of 1,667,867 base pairs and 1,590 predicted coding sequences. Sequence analysis indicates that H. pylori has well-developed systems for motility, for scavenging iron, and for DNA restriction and modification. Many putative adhesins, lipoproteins and other outer membrane proteins were identified, underscoring the potential complexity of host-pathogen interaction. Based on the large number of sequence-related genes encoding outer membrane proteins and the presence of homopolymeric tracts and dinucleotide repeats in coding sequences, H. pylori, like several other mucosal pathogens, probably uses recombination and slipped-strand mispairing within repeats as mechanisms for antigenic variation and adaptive evolution. Consistent with its restricted niche, H. pylori has a few regulatory networks, and a limited metabolic repertoire and biosynthetic capacity. Its survival in acid conditions depends, in part, on its ability to establish a positive inside-membrane potential in low pH.

Antigenic Variation↗
PubMed1997

Heat inactivation of Ku autoantigen: possible role in hyperthermic radiosensitization.

Heat shock prior, during, or immediately after ionizing radiation synergistically increases cell killing, a phenomenon termed hyperthermic radiosensitization. Recently, we have shown a constitutive DNA-binding factor in rodent cells that is inactivated by heat shock to be identical to Ku autoantigen. Ku, consisting of an Mr 70,000 (Ku70) and an Mr 86,000 (Ku80) subunit, is a heterodimeric nuclear protein and is the DNA-binding regulatory component of the mammalian DNA-dependent protein kinase DNA-PK. Recent genetic and biochemical studies indicate the involvement of Ku and DNA-PK in DNA double-strand break repair and V(D)J recombination. On the basis of these findings, we propose that heat-induced loss of the DNA-binding activity of Ku may lead to hyperthermic radiosensitization. To test this hypothesis, we examined and compared the DNA-binding activity of Ku, the DNA-PK kinase activity, and hyperthermic radiosensitization in rodent cells immediately after heat shock and during post-heat shock recovery at 37 degrees C. Our results show that the heat-induced loss of Ku-DNA binding activity correlates well with an increased radiosensitivity of the heat-shocked cells, and furthermore, the loss of synergistic interaction between heat and radiation parallels the recovery of the DNA-binding activity of Ku. On the other hand, the heat-induced decrease of DNA-PK activity did not correlate with hyperthermic radiosensitization. Our data, for the first time, provide evidence for a role of Ku protein in modulating the cellular response to combined treatments of heat shock and ionizing radiation.

Animals↗
PubMed1997

Characterization of the WW domain of human yes-associated protein and its polyproline-containing ligands.

We had previously identified the WW domain as a novel globular domain that is composed of 38-40 semiconserved amino acids and is involved in mediating protein-protein interaction. The WW domain is shared by proteins of diverse functions including structural, regulatory, and signaling proteins in yeast, nematode, and mammals. Functionally it is similar to the Src homology 3 domain in that it binds polyproline ligands. By screening a 16-day mouse embryo expression library, we identified two putative ligands of the WW domain of Yes kinase-associated protein which we named WW domain-binding proteins 1 and 2. These proteins interacted with the WW domain via a short proline-rich motif with the consensus sequence of four consecutive prolines followed by a tyrosine. Herein, we report the cDNA cloning and characterization of the human orthologs of WW domain-binding proteins 1 and 2. The products encoded by these cDNA clones represent novel proteins with no known function. Furthermore, these proteins show no homology to each other except for a proline-rich motif. By fluorescence in situ hybridization on human metaphase chromosomes, we mapped the human genes for WW domain-binding proteins 1 and 2 to chromosomes 2p12 and 17q25, respectively. In addition, using site-directed mutagenesis, we determined which residues in the WW domain of Yes kinase-associated protein are critical for binding. Finally, by synthesizing peptides in which the various positions of the four consecutive proline-tyrosine motif and the five surrounding residues were replaced by all possible amino acid residues, we further elucidated the binding requirements of this motif.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Forequarter amputation with fasciocutaneous deltoid flap reconstruction for malignant tumors of the upper extremity.

BACKGROUND: Malignant tumors of the upper extremity involving a considerable portion of the medial axillary wall may require forequarter amputation to achieve gross resection of tumor. These resections frequently leave a large defect, often requiring a split thickness skin graft or free flap to close the wound. To address this problem of wound closure, we have modified our technique and devised a reconstructive component as part of our forequarter amputation procedure. METHODS: The medical records of seven patients who underwent forequarter amputation and fasciocutaneous deltoid flap reconstruction between 1982 and 1994 were reviewed. RESULTS: All the amputation sites were completely closed with a fasciocutaneous deltoid flap without the use of additional skin grafts or free flaps. After a median follow-up of 12 months, there were no local recurrences. Three patients (43%) are alive and disease free 5, 12, and 19 months after their forequarter amputation. One patient is alive with disease after 14 months. The remaining three patients died of their disease. CONCLUSION: The fasciocutaneous deltoid flap is technically easy to perform, provides wound coverage without the use of skin grafts, and is especially useful for tumors involving the media axillary wall and in patients with previous axillary radiation.

Adult↗
PubMed1997

Modulation of steroidogenesis by chloride ions in MA-10 mouse tumor Leydig cells: roles of calcium, protein synthesis, and the steroidogenic acute regulatory protein.

It has previously been shown that omission of extracellular chloride ions during culture of rat Leydig cells markedly enhances LH-stimulated steroidogenesis. In the present study, the mechanisms of the effect of chloride omission on (Bu)2cAMP-stimulated steroidogenesis in MA-10 mouse Leydig tumor cells have been investigated. It was found that chloride omission enhanced progesterone production 2- and 4-fold in the absence and presence, respectively, of submaximally stimulating levels of (Bu)2cAMP (0.1 mM) during incubation for 2 h. This enhancement of stimulation increased continuously with time, because after 6 h, (Bu)2cAMP-stimulated progesterone production was 15-fold higher in the absence of chloride. These effects were not found in the presence of maximum stimulating levels of (Bu)2cAMP (1 mM). Omission of calcium from the incubation medium decreased (Bu)2cAMP-stimulated progesterone production by over 70% in the presence and absence of chloride. Progesterone production was still enhanced by the omission of chloride in the absence of calcium, but the effects were less marked than those in the presence of calcium. Addition of the protein synthesis inhibitor, cycloheximide, completely inhibited (Bu)2cAMP-stimulated, but not basal, steroidogenesis in the absence and presence of chloride ions during 2- and 6-h incubation. Total protein synthesis (measured by the incorporation of [3H]methionine) was 4-fold higher in cells incubated in chloride-free medium compared with that in cells incubated in chloride-replete medium in the presence of 0.1 mM (Bu)2cAMP. No effects were found on basal levels. Several proteins specific to the steroidogenic machinery were quantified in mitochondria isolated from cells incubated with and without chloride by Western blot analysis after separation by PAGE. Omission of chloride increased (4-fold) the level of the steroidogenic acute regulatory (StAR) protein in the cells incubated with (Bu)2cAMP (0.1 mM). There was no increase in either the levels or activities of cytochrome P450 cholesterol side-chain cleavage enzyme (cytP450scc) or 3beta-hydroxysteroid dehydrogenase. No effects were found on the basal level of any of the proteins measured. These results are consistent with a cAMP-dependent regulatory role of chloride ion efflux in the control of steroidogenesis, which requires protein synthesis. It is proposed that this occurs by increases in StAR protein synthesis via a general increase in cAMP-dependent protein synthesis and/or by enhancement of the steroidogenic effects of StAR.

3-Hydroxysteroid Dehydrogenases↗
PubMed1997

Impact of adopting lower-fat food choices on nutrient intake of American children.

OBJECTIVE: To compare the overall nutrient intake of American children (ages 2 to 19) who exclusively use skim milk instead of 1%, 2%, or whole milk; lean meats instead of higher-fat meats; or fat-modified products instead of full-fat products. STUDY DESIGN: A unique sorting procedure was used to categorize respondents to the 1989-1991 Continuing Survey of Food Intake by Individuals according to reported use or nonuse of certain fat-reduction strategies. Differences in intake of 23 macronutrients and micronutrients, as well as energy, by exclusive users, mixed users, and nonusers of each strategy were statistically analyzed using analysis of variance with Scheffe's test. The number of fat-reduction strategies used by the children as well as demographic characteristics also were analyzed. RESULTS: Only a small number of children qualified as exclusive users of skim milk (3%), lean meats (2%), and fat-modified products (1%). Energy intakes for all children were below 100% of the recommended dietary allowance. However, children (n = 85) who used skim milk exclusively in place of higher-fat milks closely approximated the current dietary recommendations (30% energy from fat, less than 10% from saturated fat, and less than 300 mg cholesterol) while maintaining adequate micronutrient intake and without significantly impacting energy. Children (n = 52) who used lean meats in place of higher-fat meats achieved the guideline for total fat; however, energy intake was 70% of the recommended dietary allowance and vitamin E was 63%. Children (n = 20) who use only fat-modified versions of cheese, salad dressing, cake, pudding, and yogurt made no significant impact on their energy, fat, or micronutrient intake. Of the 3299 children in the data set, only 3 qualified as users of two fat-reduction strategies and none qualified as users of all three strategies. Exclusive users of skim milk, lean meat, or fat-modified products were more likely to be female, white, and live in families with higher incomes. Those using skim milk or lean meat exclusively also were more likely to be older, whereas those exclusively using fat-modified products were younger. Furthermore, those using skim milk or fat-modified products exclusively were more likely to live in households where the head had more years of education, whereas those exclusively using lean meats were from households headed by those with slightly less years of education. CONCLUSIONS: Despite the inherent limitations of population-based food surveys (including issues of underreporting, lack of biological markers and accurate anthropometric measures, and limited nutrient databases), these results provide insight into the rate of use of certain lower-fat food choices by children and suggest exclusive use can facilitate achievement of contemporary dietary recommendations. The impact of using these fat-reduction strategies on children's overall nutrient intake differs depending on the strategy used. Use of skim milk is an economical single-food strategy that facilitates achievement of contemporary dietary guidelines while maintaining nutrient adequacy. Professional guidance is recommended for children who exclusively use lean meats to assure adequate intake of energy and vitamin E. The impact of fat-modified products needs to be monitored closely as the number of such products increases in the marketplace. Results of this study can be used by health professionals working with children and their parents to highlight the overall efficacy of dietary recommendations while alerting them to potential pitfalls.

Adolescent↗
PubMed1997

Practice variation in Swedish primary care.

OBJECTIVE: To study individual practice patterns of physicians working in primary health care for standardized simulated cases on their first visit, and relate them to resource consumption for diagnostic tests, drugs and sick leave from a combined perspective of the health care and social security systems. DESIGN: Postal questionnaire presenting six hypothetical working-age cases with symptoms of ailments common in primary care asking physicians to order diagnostic tests and procedures, drugs, follow-up appointments and sick pay. SETTING: Swedish primary health care centres. SUBJECTS: Two hundred randomly selected physicians. MAIN OUTCOME MEASURES: Activities taken by the physician-diagnostic and laboratory tests ordered, drugs prescribed, length of sick leave and the cost of these actions. RESULTS: Practice patterns varied considerably, corresponding to a six-fold difference in total cost between the "cheapest" and "most expensive" physician. The largest share was loss of production as estimated by the cost of prescribed sick leave. Physicians who practised further away from hospitals and those who had worked more years tended to prescribe more measures. However, this only explained a small portion of the observed variation, which may be due to different physician attitudes to taking risks. CONCLUSION: "Paper" cases of common medical ailments presented to primary care physicians revealed considerable differences in practice style, resulting in six-fold differences in cost of measures prescribed at first visits.

Adult↗