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Biomedical subjects

J Reiff

Publications and source records attributed to J Reiff.

9 recordsLinked to original sources
PubMed1999

Equivalent fields and scatter integration for photon fields.

Equivalent fields are often used in radiation oncology for calculation of dose. This avoids the need to make a scatter integration but has limited applicability and some inaccuracy. We have evaluated the alternative of explicit integration of phantom-scatter dose using a functional representation, sigma, of the ratio between the scatter dose and the primary dose. The independent parameters are depth and the side of the square field. The function chosen has the advantage that the integral for a right triangle is available in closed form, which simplifies the determination of the dose from phantom-scattered photons for irregular fields by summation over such triangles. This approach accounts for the influence of depth and beam quality, which the commonly used equivalent-field tables and the area-over-perimeter relation ignore. The accuracy of this procedure is determined by the accuracy of the function sigma. This has about a 1% error of total dose for high-energy x-rays. We conclude that the tables and rules can be replaced by a computer-implemented integration of the phantom-scatter dose represented by this function sigma and using sectors or right triangles. Summing the closed-form contributions from component right triangles reduces the calculation time, which is particularly desirable when many fields are employed, as for intensity-modulated techniques and inverse planning. Measurements performed on irregular MLC-shaped fields compared well with the result from calculations.

Models, Statistical↗
PubMed1999

Polymorphonuclear neutrophil chemiluminescence in whole blood from blunt trauma patients with multiple injuries.

BACKGROUND: Studies using isolated polymorphonuclear neutrophils (PMNs) indicate that trauma is associated with altered function of PMNs. Because isolation of PMNs can itself alter the function of these cells, we examined the relationships among measures of injury severity and several indices of PMN function using whole blood samples from trauma patients. METHODS: Whole blood samples were obtained from 12 blunt trauma patients with multiple injuries in the intensive care unit of a Level I trauma center within 24 hours of admission and from 11 healthy volunteers. Samples were assayed for PMN chemiluminescence (CL) in response to a complement receptor 3 (CR3)-dependent agonist and for CD11b (CR3) expression. Common clinical parameters were correlated with CL and CR3 expression. RESULTS: The CL ratio (i.e., unprimed/primed CL) was significantly correlated with initial base deficit (BD), Injury Severity Score (ISS), CR3 expression, units of packed red blood cells transfused during the interval before blood sampling, and length of intensive care unit stay (survivors only). In contrast, BD did not correlate with units of red blood cells transfused or length of stay. Similarly, ISS did not correlate with length of stay. CONCLUSION: Significant correlations were observed between CL ratios and CR3 expression, ISS, initial BD, length of stay, and units of blood given. These data suggest that measuring CL produced by PMNs in whole blood is a potentially useful way to assess injury severity. Whereas the initial BD and ISS are indicators of how badly injured a patient is at the time of entry into a trauma center, the CL ratio may be a more useful indicator of both injury severity and prognosis.

Blood Transfusion↗
PubMed1997

Maintenance and down-regulation of primed neutrophil chemiluminescence activity in human whole blood.

Priming of polymorphonuclear neutrophils (PMN) in whole blood (by tumor necrosis factor alpha and interleukin-8 for enhancement of luminol-dependent chemiluminescence induced by human complement-opsonized zymosan) was stable for 120 min. In contrast, priming of isolated PMN in plasma-free suspension for responses to opsonized zymosan, formyl-methionyl-leucyl-phenylalanine, and phorbol myristate acetate was markedly less stable. Decay of priming was not due to irreversible inactivation of the terminal CL production machinery because PMN could be reprimed by platelet-activating factor or leukotriene B4. The tumor necrosis factor-alpha-primed state of isolated PMN was stabilized by host plasma in a concentration-dependent fashion. We conclude that PMN priming results in a dynamic state that is reversible. Our findings suggest the existence of blood-borne components that may act to stabilize or modify PMN priming.

Down-Regulation↗
PubMed1995

Jungle medicine revisited: an Oklahoma medical team visits Bolivia.

Twenty-five adventurous physicians, nurses, oral surgeons, lab technicians, and lay support persons visited the remote Bolivian village of Corroico during February, 1995. During the next week, they treated 1200 patients with maladies of all types. Intestinal parasites, failure to thrive, leishmaniasis, tuberculosis, multiple dental caries, and ear, nose and throat infections comprised the majority of the conditions treated. Over $50,000 in medications were dispensed during the week.

Adolescent↗
PubMed1992

Chronic tonsillar herniation and Crouzon's syndrome.

Patients born with craniofacial syndromes such as Crouzon's syndrome will often develop hydrocephalus after their initial craniofacial reconstructive procedures. We have treated 10 patients with Crouzon's syndrome; 5 patients required a shunting procedure after cranial remodeling. Each of these 5 shunted patients later demonstrated chronic tonsillar herniation on magnetic resonance imaging studies. One of these patients exhibited signs of pseudotumor cerebri and 1 had a spastic quadriparesis. Of the 5 patients who did not require a shunt, none displayed chronic tonsillar herniation. Our evidence suggests that jugular foramen stenosis produces an increased cerebral venous turgor that leads to a cerebrospinal fluid absorption defect and hydrocephalus. After the hydrocephalus is treated the increased venous turgor remains and provides the driving force for the development of chronic tonsillar herniation.

Cerebellar Diseases↗
PubMed1983

Coffee and pancreatic cancer: an analysis of international mortality data.

This study assessed the relationship of per capita coffee imports and consumption, total dietary fat, saturated fat, cholesterol, tobacco, cigarettes, and national income for 1957-1965 to age-adjusted pancreatic cancer death rates of men and women from 22 countries in 1971-1974. With simple correlation analysis, coffee, total dietary fat, saturated fat, and national income were each significantly correlated with both male and female pancreatic cancer mortality. Bivariate partial correlation coefficients of coffee with pancreatic cancer mortality were significant (one-tailed) in 11 of 12 analyses and borderline significant in two-way analyses of variance (ANOVA) (two-tailed) controlling for each of the other variables. Saturated fat and pancreatic cancer were also significantly related in univariate analyses, and in 11 of 12 bivariate partial correlation analyses; in ANOVA, significance was borderline in 10 of 12 analyses. Total fat and pancreatic mortality were also significantly associated in most of the univariate and bivariate correlation analyses, but not in the two-way analyses of variance. The findings of this study are consistent with the hypothesis that coffee and dietary lipid are involved in the etiology of pancreatic cancer.

Adolescent↗
PubMed1983

Signs of airway obstruction during sleep and behavioral, developmental, and academic problems.

This case control study of healthy children utilized parents' reports to determine whether behavioral, developmental, or academic problems were associated with signs of partial airway obstruction (snoring, difficult or labored breathing, and mouth breathing) during sleep. Results suggest an association between the signs of airway obstruction during sleep and problems when awake. Children with behavioral, developmental, or academic problems had a significantly later bedtime hour, briefer duration of total sleep, longer night awakenings, and an increased latency to sleep, as compared to children without those problems.

Airway Obstruction↗