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Biomedical subjects

S Craig

Publications and source records attributed to S Craig.

121 records · Page 7Linked to original sources
PubMed1976

Structure and function of cholera toxin and hormone receptors.

The enterotoxin from Vibrio cholerae is a protein of 100,000 mol wt which stimulates adenylate cyclase activity ubiquitously. The binding of biologically active 125I-labeled choleragen to cell membranes is of extraordinary affinity and specificity. The binding may be restricted to membrane-bound ganglioside GM1. This ganglioside can be inserted into membranes from exogenous sources, and the increased toxin binding in such cells can be reflected by an increased sensitivity to the biological effects of the toxin. Features of the toxin-activated adenylate cyclase, including conversion of the enzyne to a GTP-sensitive state, and the increased sensitivity of activation by hormones, suggest analogies between the basic mechanism of action of choleragen and the events following binding of hormones to their receptors. The action of the toxin is probably not mediated through intermediary cytoplasmic events, suggesting that its effects are entirely due to processes involving the plasma membrane. The kinetics of activation of adenylate cyclase in erythrocytes from various species as well as in rat adipocytes suggest a direct interaction between toxin and the cyclase enzyme which is difficult to reconcile with catalytic mechanisms of adenylate cyclase activation. Direct evidence for this can be obtained from the comigration of toxin radioactivity with adenylate cyclase activity when toxin-activated membranes are dissolved in detergents and chromatographed on gel filtration columns. Agarose derivatives containing the "active" subunit of the toxin can specifically absorb adenylate cyclase activity, and specific antibodies against the choleragen can be used for selective immunoprecipitation of adenylate cyclase activity from detergent-solubilized preparations of activated membranes. It is proposed that toxin action involves the initial formation of an inactive toxin-ganglioside complex which subsequently migrates and is somehow transformed into an active species which involves relocation within the two-dimensional structure of the membrane with direct perturbation of adenylate cyclase molecules (virtually irreversibly). These studies suggest new insights into the normal mechanisms by which hormone receptors modify membrane functions.

Adenylyl Cyclases↗
PubMed1975

The general and specific humoral immune response to pulmonary aspergillosis.

The genus Aspergillus may cause one of several clinical entities in affected patients. Serum specimens from 79 patients, including 41 with aspergilloma, 28 with allergic bronchopulmonary aspergillosis, 3 with both aspergilloma and the allergic variant, and 7 with invasive or disseminated aspergillosis, were studied for antibodies to aspergillus. The ammonium sulfate test was used with a mycelial component labeled with iodine-125 derived from Aspergillus fumigatus. Complement fixation and immunodiffusion tests using a culture filtrate antigen (aspergillin) from the same species were also performed. Immunoglobulins G, A, and M and complement component C-3 were determined by radial immunodiffusion. Total serum IgE was measured by radioimmunoassay. Serum specimens from patients with aspergilloma manifested increased binding to the radio-labeled mycelial component, multiple precipitin bands, and/or increased complement fixation titers to aspergillin. Serum concentrations of IgG and IgA were increased. Patients with allergic bronchopulmonary aspergillosis were characterized by moderately increased binding to the radio-labeled mycelial component, a paucity of precipitating and complement-fixing antibody to aspergillin, and increased total serum IgE. Serum from patients with locally invasive or disseminated aspergillosis had increased concentrations of C-3 and variable binding to the radiolabeled mycelial component, depending on the duration of the disease process. Use of a battery of tests with both mycelial and culture filtrate antigens enhanced detection of circulating aspergillus antibody.

Ammonium Sulfate↗
PubMedDate not supplied

Psychosocial correlates of physical activity among fifth and eighth graders.

BACKGROUND: Identification of the factors that influence children's participation in vigorous activity is essential to the development of effective intervention strategies aimed at the prevention of cardiovascular disease and obesity. METHODS: Correlates of intent to participate in vigorous activity were assessed among 310 fifth and eighth graders in Cambridge, Massachusetts, through the development and administration of a questionnaire based on the Theory of Planned Behavior, an extension of the Theory of Reasoned Action, which includes the domain of perceived behavioral control (how easy or difficult it is to engage in vigorous activity). Heights and weights were measured and questionnaires were completed during physical education classes. RESULTS: Perceived behavioral control and attitude predicted children's intent to participate. How much a child agreed s/he was good at doing vigorous activity predicted perceived behavioral control. In each grade, girls reported being less good at vigorous activity than did boys. Eighth-grade girls reported significantly fewer hours of vigorous activity than did eighth-grade boys. CONCLUSIONS: Our findings suggest that gender differences related to intent to participate in vigorous activity, perceived behavioral control, and sense of competency are evident in eighth grade and may begin in fifth grade. These gender differences in perception therefore precede the gender difference in participation in vigorous activity demonstrated among ninth graders in the 1990 Youth Risk Behavior Survey. Promotion of activities children enjoy, and in which they feel a sense of competency, is likely to sustain participation in vigorous activity throughout adolescence and possibly reduce the prevalence of obesity.

Adolescent↗
PubMedDate not supplied

One-year outcomes of Project Towards No Drug Abuse.

OBJECTIVES: This paper presents the 1-year outcomes evaluation of Project Towards No Drug Abuse (Project TND), a large-scale indicated drug abuse prevention program in southern California applied to continuation high school youth, who are at high risk for drug abuse. METHODS: The efficacy of nine-lesson health motivation--social skills--decision-making curriculum was evaluated in a three-condition experimental design. Twenty-one schools were randomly assigned by block to one of three conditions--standard care (control), classroom program, and classroom program plus a semester-long school-as-community component. A pretest was followed by a 3-week-long drug abuse prevention program and then a posttest at 14 continuation high schools. The 7 standard care schools received only the pretest followed by the posttest (same time duration). Subjects were followed up 1 year later. RESULTS: Changes in use of cigarettes, alcohol, marijuana, and hard drugs were assessed in a pretest-1-year follow-up time interval. The follow-up rate was 67% (analysis n = 1,074). Indicated preventive effects were found on alcohol and hard drug use. No differences were found across the two program conditions. CONCLUSIONS: Project TND is the first program to demonstrate 1-year self-reported behavioral effects on alcohol use and hard drug use among older, high-risk youth by using a school-based, limited-session model.

Adolescent↗
PubMedDate not supplied

Recombinant-derived interleukin-1 alpha stabilized against specific deamidation.

Recombinant-derived human interleukin-1 alpha (IL-1 alpha), purified from Escherichia coli, was resolved by isoelectric focusing on polyacrylamide gels into two species of isoelectric points (pI) 5.45 and 5.20, which constituted approximately 75% and approximately 25% of the total IL-1 alpha protein respectively. The pI 5.45 and pI 5.20 species were separated by chromatofocusing and subjected to N-terminal sequence analysis. The pI 5.45 species contained the expected Asn residue at position 36 of the mature protein sequence whereas the pI 5.20 species contained an Asp residue at the same position. A mutant protein in which Asn-36 was substituted for a Ser residue was isolated from E. coli and shown to be homogeneous on isoelectric focusing analysis with a pI = 5.45. 1H-n.m.r. and circular dichroism analyses of wild-type and the mutant IL-1 alpha indicated a similar conformation which was also indicated by the identical receptor binding affinities of IL-1 alpha with Asn, Asp or Ser in position 36. The mutant protein was stabilized against specific base-catalysed and temperature-induced deamidation, and may be more suitable than the wild-type position for physical and structural studies.

Amino Acids↗
PubMedDate not supplied

Seven stars in the healthcare system: a lesson in trajectories.

Massive reorganization in the healthcare industry has created a new series of high-level, multi-talented managers. Many have risen from the ashes of change, taking new positions and shifting from positions with a single focus to managing complex administrative matrices. Seven who have been through the reorganization process comment on where they have come from and what they learned from their experience. Their distilled advice: take advantage of further schooling, OJT, hospital association seminars and workshops. Delegate; communicate; don't be afraid to admit you don't have all the technical knowledge at your fingertips. Above all, remember you are to direct the work, not do the work itself.

Career Mobility↗
PubMedDate not supplied

The way it was: radiology administrators remember.

Radiology Management wanted to understand what it was like to be a radiology administrator 24 years ago. What events were taking place in healthcare that inspired a small group of people to come together to form an organization for their mutual benefit? What role have changes in technology and the industry in general played over the years? Two roundtable discussions were held earlier this year as forums for AHRA members to come together and reminisce about the organization and the profession. One such discussion was held in Sudbury, Mass. where participants included Louise P. Broadley, FAHRA; Monte G. Clinton, FAHRA; Cecilie Godderidge, FAHRA; Chuck Mitchell, FAHRA; and Tammy Waldhauser. In addition, William W. Wheeler, FAHRA; David A. Stone, FAHRA; and Billy Wesson joined the conversation by telephone. The other roundtable was held during the Western Region's 25th anniversary meeting in San Diego in April, and included Lois A. Haas, FAHRA; Stephen J. Hage, FAHRA; Jack Healy; Merlin C. Heinselman, FAHRA; Martin T.J. Hilger, FAHRA; Brenda S. Holden, FAHRA; Sharon K. Johnson, FAHRA; Merle D. Meland, FAHRA; James Mom; Bobbie O'Boyle, FAHRA; Paula Osborn, representing Royce Osborn, FAHRA; Roland W. Rhynus, FAHRA; Mark Rutherford and Richard Steuve. As old friends will do when they get together after many years, these two groups on opposite sides of the country shared their stories with both humor and pathos. They reminisced about people they had known and hospitals where they had worked. They recalled some good times and some not so good, as they looked back at the beginning of an organization first called American Hospital Radiology Administrators. Mostly they talked of the many changes that have taken place over the years in healthcare and for the profession of radiology administration. Radiology Management is pleased to share some of those conversations here.

Hospital Administrators↗
PubMedDate not supplied

The fetal and neonatal outcomes of Rhesus D antibody affected pregnancies in Northern Ireland.

It has been suggested that routine antenatal prophylactic anti-D should be introduced for prevention of Rhesus D (RhD) haemolytic disease. Before making changes to the current prevention program it is important, therefore, to have up-to-date data on affected infants. Pregnant women with anti-D antibodies between September 1994 and February 1997 were identified by the Northern Ireland Blood Transfusion Service. The records of 124 women and 130 babies were examined. 26% of planned deliveries occurred in hospitals without paediatric cover. Rhesus isoimmunisation affected 78 babies. Fifty-nine infants were admitted to one of seven neonatal units. There were 2 stillbirths and 1 neonatal death. Two infants have severe neurodevelopmental delay. There is still significant morbidity associated with RhD haemolytic disease. Care for RhD affected pregnancies should be centralised to guarantee training opportunities and maintenance of expertise. The current management of these pregnancies should be re-examined before changing the Rhesus prevention program.

Erythroblastosis, Fetal↗