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Biomedical subjects

S Larson

Publications and source records attributed to S Larson.

At least 55 records · Page 3Linked to original sources
PubMed1992

Crystallization and preliminary X-ray analysis of human endothelin.

Endothelin, a potent regulator of vasoconstriction and hypertension, is a naturally produced peptide of 21 amino acids containing two disulfide bonds. We have crystallized endothelin from humans using the vapor-diffusion technique, characterized the crystals by X-ray diffraction analysis, and have collected the X-ray intensities to a resolution of 1.8 A. The crystals, which demonstrate physical properties similar to most protein crystals and have a comparable solvent content, are hexagonal prisms that frequently grow to lengths of 400 microns and widths of 150 microns. The space group of the crystals is P6(1)22 (or P6(5)22), with a = 27.4, c = 79.6 A. There is one molecule of endothelin in the asymmetric unit of the crystals.

Crystallization↗
PubMed1992

Preliminary crystallographic study of peanut peroxidase.

The cationic isozyme of peroxidase isolated from suspension cultures of peanut cells is a heme-containing and calcium-dependent glycoprotein having four covalently attached oligosaccharide chains. Attempts were made to crystallize the glycoprotein for X-ray diffraction analysis, and these have met with some success. Crystals have now been grown that are suitable for a full three-dimensional structural analysis. The crystals are thin plates and we have shown them to be of the orthorhombic space group P2(1)2(1)2(1) with a = 48.1, b = 97.2, c = 146.2 A. The crystals diffract to beyond 2.8 A resolution, appear to be stable to lengthy X-ray exposure, and contain two molecules of 40,000 daltons each in the asymmetric unit.

Arachis↗
PubMed1992

Massage reduces anxiety in child and adolescent psychiatric patients.

A 30-minute back massage was given daily for a 5-day period to 52 hospitalized depressed and adjustment disorder children and adolescents. Compared with a control group who viewed relaxing videotapes, the massaged subjects were less depressed and anxious and had lower saliva cortisol levels after the massage. In addition, nurses rated the subjects as being less anxious and more cooperative on the last day of the study, and nighttime sleep increased over this period. Finally, urinary cortisol and norepinephrine levels decreased, but only for the depressed subjects.

Adjustment Disorders↗
PubMed1992

Family violence and the evaluation of behavioral concerns in a pediatric primary care clinic.

The goals of this study were to determine 1) the prevalence of exposure to intrafamilial violence among children attending a pediatric primary care clinic; 2) the prevalence of psychosocial distress among mothers bringing their children to the clinic; 3) the extent to which pediatricians are aware of family violence and maternal distress among their patients; and 4) whether families reporting violence are more likely to report behavioral or emotional problems with their children. The study focused on 243 mothers and their children who made scheduled visits to an inner-city, hospital-based pediatric residents' continuity clinic. The children ranged in age from 6 months to 14 years, with 69% of the children 2 years of age or younger. Parents answered questions about their own and their child's psychosocial functioning, including a modified version of the Conflict Tactics Scale, an instrument used to measure the prevalence of intrafamilial violence. Physicians independently rated parent and child psychosocial health and the likelihood of violence in the family. Forty percent of mothers said their family in the past year had experienced at least one episode of the five most serious types of violence described on the Conflict Tactics Scale. Mothers reporting these levels of violence were more likely to report psychosocial distress in their own lives as well as those of their children. Furthermore, family violence predicted maternal concern for child behavior even after accounting for the increased maternal distress associated with violence. Physicians had difficulty predicting which mothers would report violence (sensitivity 27%, specificity 81%) or which mothers would report concern about child behavior and emotional health. The authors concluded that an instrument like the Conflict Tactics Scale might both add to physicians' awareness of family violence and help explain some parental concerns about the behavior or emotional health of apparently asymptomatic children.

Adolescent↗
PubMed1991

Characterization of crystals of an Fab fragment of a murine monoclonal antibody.

The Fab fragment of an antibody, made against an E2-specific feline infectious peritonitis virus neutralizing antibody, has been crystallized in a form suitable for X-ray diffraction analysis from PEG 4000 using vapor diffusion methods. The Fab fragment crystals diffract to about 2.9 A resolution and are of triclinic space group P1. Unit cell dimensions, by which the reciprocal lattice can be indexed, are a = 57.16 A, b = 70.85 A, c = 75.81 A, alpha = 85.11 degrees, beta = 121.28 degrees and gamma = 116.33 degrees. There are two Fab fragments comprising the asymmetric unit of the crystals. The presence of a pseudo-mirror plane in the diffraction pattern suggests the presence of at least an approximate dyad axis relating the two Fab fragments within the asymmetric unit.

Animals↗
PubMed1991

Characterization of crystals of an intact monoclonal antibody for canine lymphoma.

A monoclonal antibody of the subclass IgG2a specific for canine lymphoma cells has been crystallized by vapor diffusion from polyethylene glycol 8000. the crystals, which occasionally measure nearly a millimeter on edge, have been examined by X-ray diffraction. The crystals are of triclinic space group P1 with unit cell parameters of a = 66.39 A, b = 77.34 A, c = 101.42 A, alpha = 87.60 degrees, beta = 92.55 degrees, gamma = 97.54 degrees and cell volume of V = 4.84 x 10(5) A3. There is one entire antibody molecule as the asymmetric unit of the crystals. Three-dimensional X-ray diffraction data have been collected to 2.8 A resolution and a self rotation function calculation shows a pronounced peak indicating at least an approximate non-crystallographic dyad axis.

Animals↗
PubMed1991

Preliminary investigation of crystals of the neutral lipase from Pseudomonas fluorescens.

The neutral lipase from the bacteria Pseudomonas fluorescens, marketed under the trade name LpL-200S, has been crystallized in a form suitable for X-ray diffraction analysis from 35% n-propanol at pH 8.5. The crystals are monoclinic prisms and are of space group C2 with a = 91.00 A, b = 47.17 A, c = 35.21 A and beta = 121.43 degrees. There is one molecule of the protein as the asymmetric unit of the crystals. The diffraction pattern extends to at least 1.6 A resolution and the crystals are extremely robust in terms of X-ray exposure.

Crystallization↗
PubMed1991

The febrile alcoholic in the emergency department.

The authors retrospectively reviewed the charts of 31 alcoholic patients admitted with fever without a defined source. In our population 58% of patients were subsequently found to have an infectious cause for their fever. Pneumonia was the most common infection, but occult urinary tract infections were seen surprisingly often. Noninfectious but serious disorders, such as delirium tremens, prolonged postictal state, and subarachnoid hemorrhage, were also common. Infectious and noninfectious causes commonly coexisted. The most common noninfectious cause was alcohol withdrawal, with or without seizures. The authors believe that indigent, malnourished, chronic alcoholics with fever for which a source cannot be readily identified, should usually be admitted to the hospital for observation and to await culture results.

Adult↗
PubMed1988

Problems associated with collecting drinking water quality data for community studies: a case example, Fresno County, California.

This paper discusses methodology in developing exposure data for the water supply contaminant dibromochloropropane (DBCP) in Fresno County, California. There are 532 drinking water systems (49 large and 483 small) within Fresno County plus 14,000 private wells. We determined the number of wells per system, the output per well, and the population served by each system. The task of deriving water quality estimates for each census tract was complicated by the fact that a single census tract can be served by more than one system; each system usually has more than one well; and a single well can have several episodes of testing for various contaminants. We calculated a series of weighted averages for concentrations of DBCP, arsenic, and nitrates for each census tract, using water production figures for each well as the weighting factor. Water quality data were derived from a total of 14,861 laboratory reports, although the majority did not report on all contaminants. Mean DBCP levels ranged from 0.0041 ppb to 5.7543 ppb among the census tracts. We found no correlation between DBCP levels per census tract compared to either arsenic or nitrates. We believe that we made as complete an exposure assessment as practically feasible.

Arsenic↗