Season of birth and cockroach allergen sensitization in children with asthma.
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Adolescent↗
Biomedical subjects
T Karrison
Publications and source records attributed to T Karrison.
Skin test reactivity to indoor allergens as a marker of asthma severity in children with asthma.
BACKGROUND: Specific IgE responses to common indoor aeroallergens in children with asthma have been found to be associated with acute asthma. OBJECTIVE: The purpose of this study was to examine the association between asthma severity and skin test reactivity to four common indoor allergens. METHODS: The charts of 139 asthmatic children, aged 5 to 18 years, seen in a pediatric allergy clinic were reviewed to obtain the results of skin tests to cat, dog, cockroach, and dust mite allergens, FEV1, anti-asthma medication requirements and demographic characteristics. Logistic regression for ordinal data was used to examine the association between skin test reactivity and asthma severity (mild, moderate or severe) as determined from FEV1 and medication usage. RESULTS: The rate of allergen sensitivities were dust mite 55%, cockroach 50%, cat 29% and dog 17%. Children with positive skin test to cat allergen were more likely to have a higher asthma severity rating than children with a negative cat allergen skin test [proportional odds ratio (OR) = 3.0, 95% confidence interval (CI) = 1.4 to 6.1, P = .003]. This association remained significant after we controlled for skin test reaction to the other three allergens and various sociodemographic factors (adjusted OR = 3.0, 95% CI = 1.3 to 7.2, P = .013). The ORs for sensitivity to dog, cockroach, and dust mite allergen did not differ significantly from one, but children who were sensitized to all four allergens had an OR of 4.8 (95% CI = 1.3 to 18, P = .019) relative to children who were not sensitized to any of the four allergens. This association also remained significant after controlling for sociodemographic variables (P = .030). CONCLUSION: Children with combined sensitivity to cat, dog, dust mite, and cockroach allergens were at increased risk of having more severe asthma. Our data also suggest that sensitization to cat allergen per se is a risk factor for more severe disease in these asthmatic children.
Adolescent↗
Cockroach allergen (Bla g 1) in school dust.
BACKGROUND: Cockroach allergen, Bla g 1, is an important indoor allergen. Although household exposure has been documented, little is known about the potential for exposure outside the home. OBJECTIVE: We investigated the settled dust concentration of Bla g 1 in 147 samples collected from classrooms, kitchens, cafeterias, and other sites in four primary schools in the city of Baltimore. METHODS: School authorities were questioned about characteristics of schools, teachers, and students, as well as cockroach control and cleaning procedures. Settled dust samples were collected with a hand-held vacuum cleaner from the floors of all classrooms, food-related areas, and other sites of the schools over a 3-week period. A sample collection in each school took 1 to 2 days. Dust samples from each room were pooled and analyzed as a single sample for Bla g 1 by using a two-site monoclonal ELISA. RESULTS: One hundred two (69%) of the 147 samples had detectable Bla g 1 and were within the range reported by other investigators in inner city homes. There was no difference between the median levels of Bla g 1 in three schools: school 1 (5.2 U/gm), school 2 (3.0 U/gm), and school 4 (2.7 U/gm); but school 3 had a significantly lower level (< 0.8 U/gm, p < 0.001). The median level from the food-related areas was significantly higher than the median classroom level (p = 0.048). School 3 had fewer students on subsidized lunch, fewer African-American students, and fewer students per teacher. Bla g 1 levels were compared in the different schools while controlling for potential confounding variables by a stepwise multiple regression analysis with a logit model for ordinal responses. On the basis of this analysis, Bla g 1 levels in schools 1, 2, and 4 differed significantly from levels in school 3 (p < 0.001 in each case). Food-related areas had significantly higher levels than classrooms (p = 0.048). Floor level, the presence of a sink, and the presence of carpeting did not have significant effects. CONCLUSIONS: We conclude that Bla g 1 is detectable at potentially significant concentrations in some inner city schools. Furthermore, the level of exposure is different between different schools and between sites within individual schools.
Allergens↗
Sensitization to indoor allergens and the risk for asthma hospitalization in children.
BACKGROUND: Hospitalization for asthma continues to present a major health problem despite advances in our understanding that asthma is an inflammatory disease of the bronchi and that exposure to specific allergens can induce and worsen this inflammation. The role of sensitization to specific indoor allergens and hospitalization for acute asthma in children is unclear. OBJECTIVE: The purpose of this study was to evaluate the independent contributions of sensitization to specific indoor allergens among children with asthma to the risk of hospitalization for asthma. METHODS: The charts of 138 consecutive children with asthma, aged 5 to 18 years, seen at pediatric allergy clinics were reviewed to obtain the results of skin tests to cat, dog, cockroach, and dust mite allergens and the history of hospitalization for asthma within the year prior to the clinic visit. Logistic regression analysis was used to examine the association between indoor allergen sensitivity and other factors, and the risk of hospitalization for asthma. RESULTS: In univariate analyses, hospitalization for asthma was significantly associated with cockroach sensitivity (odds ratio [OR] = 2.2; 95% confidence interval [CI] = 1.1, 4.3); cat sensitivity (OR = 2.9; CI = 1.3, 6.4); black race (OR = 2.4; CI = 1.1, 5.1); public aid/self pay (OR = 2.3; CI 1.1, 4.9) and age, (OR [per year increase in age] = 0.8; CI = 0.7, 0.9). In a stepwise multiple logistic regression analysis, only cat sensitivity (OR = 3.8; CI = 1.5, 9.2), age (OR = 0.8; CI = 0.7, 0.9) and race (OR = 3.2; CI = 1.4, 7.5) entered into the model as significant independent predictors. CONCLUSION: Sensitivity to cat allergen may be an important determinant for asthma hospitalization in children. Sensitization to cockroach allergen per se was not found to be an independent risk factor. As observed in previous studies, younger and black children were at increased risk of hospitalization for asthma.
Adolescent↗
The PATHWAYS church-based weight loss program for urban African-American women at risk for diabetes.
OBJECTIVE: This study was carried out to test the effectiveness of PATHWAYS, a weight loss program designed specifically for urban African-American women, when administered in urban churches by trained lay facilitators. RESEARCH DESIGN AND METHODS: Thirty-nine obese women were recruited from three urban African-American churches. After randomization and the collection of baseline data on weight and lifestyle practices, subjects in the experimental group (n = 19) were assigned to receive a 14-week weight loss program (PATHWAYS) conducted by trained lay volunteers; control group subjects (n = 20) were put on a waiting list to receive the program at the conclusion of the study period. RESULTS: Of the 39 women enrolled, 15 experimental group subjects and 18 control group subjects were available for posttreatment data collection. After completing the program, PATHWAYS participants lost an average of 10.0 lb, and the control group subjects gained an average of 1.9 lb. Posttreatment difference in weight loss between the groups was statistically significant (P < 0.0001). Waist circumference among PATHWAYS participants decreased 2.5 inches, while waist circumference among control group subjects remained relatively the same. This difference between the groups was statistically significant (P < 0.05). CONCLUSIONS: A weight loss program administered by trained lay volunteers was effective in producing significant and clinically meaningful weight loss among African-American women who often do not benefit from typical weight loss programs. Ongoing research is focusing on whether the weight loss can be maintained or enhanced through monthly reinforcement sessions.
Black or African American↗
Confidence intervals for median survival times under a piecewise exponential model with proportional hazards covariate effects.
Brookmeyer and Crowley derived a non-parametric confidence interval for the median survival time of a homogeneous population by inverting a generalization of the sign test for censored data. The 1-alpha confidence interval for the median is essentially the set of all values t such that the Kaplan--Meier estimate of the survival function at time t does not differ significantly from one-half at significance level alpha. Here I extend the method to incorporate covariates into the analysis by assuming an underlying piecewise exponential model with proportional hazards covariate effects. Maximum likelihood estimates of the model parameters are obtained via iterative techniques, from which the estimated (log) survival curve is easily constructed. The delta method provides asymptotic standard errors. Following Brookmeyer and Crowley, I find the confidence interval for the median survival time at a specified value of the covariate vector by inverting the sign test. I illustrate the methods using data from a clinical trial conducted by the Radiation Therapy Oncology Group in cancer of the mouth and throat. It is seen that the piecewise exponential model provides considerable flexibility in accommodating to the shape of the underlying survival curve and thus offers advantages to other, more restrictive, parametric models. Simulation studies indicate that the method provides reasonably accurate coverage probabilities.
Age Factors↗
Comparison of median survival times with adjustment for covariates.
Brookmeyer and Crowley derived a non-parametric confidence interval for the median survival time of a homogeneous population by inverting a generalization of the sign test for censored data. The 1 - alpha confidence interval for the median is essentially the set of all values t such that the Kaplan-Meier estimate of the survival curve at time t does not differ significantly from one-half at the two-sided alpha level. Su and Wei extended this approach to the two-sample problem and derived a confidence interval for the difference in median survival times based on the Kaplan-Meier estimates of the individual survival curves and a 'minimum dispersion' test statistic. Here, I incorporate covariates into the analysis by assuming a proportional hazards model for the covariate effects, while leaving the two underlying survival curves virtually unconstrained. I generate a simultaneous confidence region for the two median survival times, adjusted to any selected value, z, of the covariate vector using a test-based approach analogous to Brookmeyer and Crowley's for the one-sample case. This region is, in turn, used to derive a confidence interval for the difference in median survival times between the two treatment groups at the selected value of z. Employment of a procedure suggested by Aitchison sets the level of the simultaneous region to a value that should yield, at least approximately, the desired confidence coefficient for the difference in medians. Simulation studies indicate that the method provides reasonably accurate coverage probabilities.
Analysis of Variance↗
The treatment of rheumatic carditis: a review and meta-analysis.
We performed a meta-analysis of the literature on the treatment of established rheumatic carditis to determine if corticosteroid therapy is superior to salicylates in preventing the sequela of inflammation--valvular damage. We identified 22 reports of comparative trials published since the introduction of corticosteroids in 1949. Five of the 22 studies met the criteria we established for the meta-analysis, which included using randomization and a 1-year follow-up for the presence of a new pathologic apical systolic murmur. Based on the meta-analysis, the advantage of corticosteroid treatment over salicylates in preventing a pathologic murmur at 1 year posttreatment is not statistically significant (estimated odds ratio 0.88; 95% confidence interval: 0.53 to 1.46). However, the meta-analysis is dominated by 1 large negative trial, and there was significant heterogeneity in the results obtained from the studies in the meta-analysis; thus, the question of whether corticosteroid therapy is marginally superior to salicylates for the prevention of valvular heart disease from rheumatic fever remains open.
Adrenal Cortex Hormones↗
Insulin secretory defects in polycystic ovary syndrome. Relationship to insulin sensitivity and family history of non-insulin-dependent diabetes mellitus.
The increased prevalence of non-insulin-dependent diabetes mellitus (NIDDM) among women with polycystic ovary syndrome (PCOS) has been ascribed to the insulin resistance characteristic of PCOS. This study was undertaken to determine the role of defects in insulin secretion as well as familial factors to the predisposition to NIDDM seen in PCOS. We studied three groups of women: PCOS with a family history of NIDDM (PCOS FHx POS; n = 11), PCOS without a family history of NIDDM (PCOS FHx NEG; n = 13), and women without PCOS who have a family history of NIDDM (NON-PCOS FHx POS; n = 8). Beta cell function was evaluated during a frequently sampled intravenous glucose tolerance test, by a low dose graded glucose infusion, and by the ability of the beta cell to be entrained by an oscillatory glucose infusion. PCOS FHx POS women were significantly less likely to demonstrate appropriate beta cell compensation for the degree of insulin resistance. The ability of the beta cell to entrain, as judged by the spectral power for insulin secretion rate, was significantly reduced in PCOS FHx POS subjects. In conclusion, a history of NIDDM in a first-degree relative appears to define a subset of PCOS subjects with a greater prevalence of insulin secretory defects. The risk of developing NIDDM imparted by insulin resistance in PCOS may be enhanced by these defects in insulin secretion.
Adult↗
The correlation between donor characteristics and the success of human islet isolation.
Clinical islet allotransplantation is dependent on the ability to achieve a high yield and purity of islets isolated from human cadaver pancreas donors. The aim of this study was to determine the factors influencing the pancreas prior to islet isolation that may alter yield and purity. The results of 50 consecutive islet isolations from cadaver donor human pancreati at the University of Chicago Medical Center from December 1991 to April 1993 were analyzed. All pancreati were first offered for whole pancreas transplantation before being considered for islet isolation. Human pancreatic islet isolation was accomplished by a modified automated method. Some islet isolations resulted in a high islet yield but low islet purity. Other resulted in well-purified islets, but a low yield. Arbitrarily, successful islet isolation is defined as that yielding over 250,000 islet equivalents (EQN) with a purity of at least 80%. The success rate of human pancreatic islet isolation was 70%. The mean final islet yield obtained from these 50 pancreati was 300,000 +/- 131,000 islet EQN. The mean purity of the final preparation was 73% +/- 25%. By univariate analysis, five factors were found to affect significantly the yield, purity, or overall success rate of islet isolation: organ cold ischemic time, donor age, donor plasma glucose levels, donor body weight, and cause of donor death. Even when islet isolation was successful, the function of islets from hyperglycemic and older donors appear to be impaired both in vitro and in vivo. These results suggest that islet yield and purity are affected by multiple donor-related factors. Even when adequate yield and purity are obtained, islet function is also dependent on donor variables.
Adolescent↗
Mode of delivery and perinatal results in breech presentation.
OBJECTIVES: Our purpose was to evaluate the outcome of deliveries with fetuses in breech presentation at labor and to compare the results by route of delivery. Specially reviewed were fetuses weighing > or = 1500 gm. STUDY DESIGN: An observational study of consecutive cases of all singleton pregnancies and twin pregnancies with the first fetus presenting in breech delivered at Chicago Lying-In Hospital from July 1980 to December 1987 was performed. Crude perinatal mortality and effect of mode of delivery (cesarean vs vaginal) by weight were compared after correction for nonpreventable causes. A further correction was made for fetuses weighing > or = 1500 gm by excluding all cases of fetal distress from the cesarean section group. All clinically relevant factors were evaluated. Statistical methods included comparison of frequencies in the two groups by chi 2 and Fisher exact tests and comparison of means by two-sample t tests. RESULTS: Of 21,380 deliveries, 843 (3.9%) presented by the breech. Forty-four percent were delivered vaginally; 8.4% were first twins. There were 51% preterm infants, and 24% had clinical distress. Crude perinatal mortality was 24%; 8% stillborns, 10% from prematurity, and 6% from other causes, including lethal congenital malformations. The corrected perinatal mortality was 15%. Vaginal deliveries had a higher 5-minute depression rate (32% vs 24%) and corrected perinatal mortality (23% vs 9.6%); however, fetal weights were significantly lower. There were no differences in outcomes for newborns weighing > or = 1500 gm by route of delivery; all five neonatal deaths in this subgroup occurred among the abdominal deliveries. CONCLUSIONS: The very poor perinatal outcomes in breeches are primarily related to factors other than breech presentation. Route of delivery for infants weighing > or = 1500 gm does not influence neonatal outcome; thus cesarean section solely for breech presentation in this subgroup does not appear to be justified.
Adolescent↗
Factors influencing neonatal outcomes in the very-low-birth-weight fetus (< 1500 grams) with a breech presentation.
OBJECTIVES: Our purpose was to evaluate factors that may influence perinatal outcomes in the very-low-birth-weight infant with breech presentation. STUDY DESIGN: An observational study that included all consecutive singletons and twins with the first fetus with breech presentation weighing between 500 and 1500 gm delivered at Chicago Lying-In Hospital from July 1980 to December 1987 was performed. Uncorrected and corrected perinatal mortality and morbidity were calculated. After correction, the effect of mode of delivery (vaginal versus cesarean section) was studied. A further correction was made by excluding cesarean sections performed for fetal distress. Statistical methods included chi 2 and Fisher exact tests and logistic regression analyses to calculate unadjusted and adjusted odds ratios. RESULTS: Of the 262 fetuses studied, nearly 60% were delivered vaginally and were of younger gestational age and lower fetal weight (300 gm) than those delivered abdominally. Forty-four percent weighed < or = 800 gm, and the perinatal mortality rate was 64.5% (53.3% after correction). Vaginal delivery had higher rates of depression, respiratory distress syndrome, and death. Prematurity was the most frequent cause of neonatal death. The corrected neonatal mortality was similar to the total inborn population of our neonatal intensive care unit for the same years. Logistic regression analyses revealed that the differences in outcomes between the two groups were primarily related to effects of gestational age, fetal weight, and year of delivery. After these factors were adjusted for, the odds of neonatal death for vaginal delivery compared with cesarean delivery were not significantly different (odds ratio 1.4, 95% confidence interval 0.6 to 3.5, p = 0.48). However, in the subgroup in footling attitude the differences were much greater, with an adjusted odds ratio of 3.2 (95% confidence interval 0.7 to 14.9, p = 0.13). CONCLUSION: The exceedingly poor perinatal outcomes of very-low-birth-weight breech infants are mainly related to antenatal deaths (22%), extremely low birth weight (44%), congenital malformations, and premature labor, not to the breech presentation. The route of delivery did not significantly influence outcome among complete and frank attitudes; abdominal delivery may offer some benefit for footlings. Prematurity is the primary cause of death of normal very-low-birth-weight breech-delivered infants.
Birth Weight↗
Delta F508 genotype does not predict disease severity in an ethnically diverse cystic fibrosis population.
OBJECTIVE: As part of a study to determine population-based frequencies of CFTR mutations in an ethnically diverse, midwestern cystic fibrosis (CF) population, clinical histories were studied in 119 CF patients. METHODOLOGY: We sought to examine the association between genotype as characterized by the delta F508 and 11 other commonly occurring mutations and clinical parameters including age at diagnosis, clinical presentation, sweat chloride level, chest roentgenogram score, clinical scores, pulmonary function test results, percent weight for height, and presence of associated CF complications. RESULTS: Age at diagnosis of CF was significantly associated with homozygosity for delta F508 (mean age at diagnosis +/- SE: 1.7 +/- 0.3 years for delta F508/delta F508 vs 3.9 +/- 0.9 years for delta F508/other and other/other; P = .03). No other age-adjusted clinical parameter was significantly associated with delta F508 or any other genotype. CONCLUSION: These data suggest that in this sample of CF patients, delta F508 genotype is not predictive of disease severity. The lack of association between disease severity and genotype in this ethnically diverse sample may reflect the presence of more severe undetected mutations in our sample, or the effects of modifying genes at other, non-CF loci.
Adolescent↗
Acute toxicity during external-beam radiotherapy for localized prostate cancer: comparison of different techniques.
PURPOSE: The chronic and acute toxicities associated with conventional radiotherapy of localized prostate cancer are well documented. However, the degree and incidence of toxicities with conformal techniques are not known. Studying side effects associated with modern radiotherapeutic techniques is more important now since there has been a general trend to use computerized tomography-based techniques in recent years; beam's eye view-based conformal techniques are also becoming more commonplace. It is possible that the local disease control can be improved with the delivery of higher doses than currently used. Conformation of the treatment volume to the target volume may facilitate such dose-escalation. However, prior to such dose-escalation, it is important to know the toxicities associated with such techniques with conventional doses. METHODS AND MATERIALS: We have compared week-by-week acute toxicities associated with conventional (Group A, 16 patients), computerized tomography-based, manual (Group B, 57 patients) and beam's eye view-based (Group C, 43 patients) techniques during 7 weeks of radiotherapy. Group B and C patients were treated contemporaneously (1988-1990). RESULTS: Acute side effects gradually increased from week 1 through weeks 4-5 and generally declined or plateaued after that. The incidence of acute toxicities was significantly less with the beam's eye view/based technique than with the other two methods. For instance, the percentages of Grade 2 acute genitourinary toxicities for Groups A, B, and C were as follows: Week 1-0, 0, 0; Week 2-6, 0, 0; Week 3-6, 9, 2; Week 4-12, 14, 9; Week 5-35, 14, 9; Week 6-31, 16, 7; Week 7-33, 8, 8, respectively. The p values associated with differences in acute genitourinary toxicities for Weeks 1-7 using chi-square test were 0.072, 0.627, 0.389, 0.538, 0.123, 0.06, and 0.012; the p values for acute gastrointestinal toxicities were 0.512, 0.09, 0.031, 0.031, 0.003, < 0.0001, and 0.004, respectively. Pairwise comparison (Wilcoxon rank-sum test) showed statistically significant lower acute toxicity in Group C than Group B (e.g., p values, Weeks 1-7 for gastrointestinal toxicity: 0.633, 0.056, 0.010, 0.014, < 0.0001, < 0.0001, and < 0.0001, respectively) in the latter part of the treatment course. No correlation was found between the extent of toxicity and the patient age or the overall treatment time. Also, no correlation was found between the degree of toxicity and the radiation dose and fraction size, within the narrow ranges used (65-70 Gy and 180-200 cGy, respectively). A trend suggesting increased severity of toxicity with increase in the volume of treatment was seen. CONCLUSION: The findings in this retrospective study need to be confirmed by other prospective studies.
Acute Disease↗
Autoantibodies and pregnancy history in a healthy population.
OBJECTIVE: Our purpose was to determine whether the presence of autoantibodies is associated with pregnancy history in healthy adults. STUDY DESIGN: Antibodies against phospholipid, histone, and nucleotide antigens were determined in 102 male and 99 female subjects. The effects of age, sex, marital status, and pregnancy history on antibody positivity were assessed. RESULTS: Women showed higher levels of autoantibodies, but differences were not statistically significant in this sample. Age was not associated with antibody positivity in men. In women age was associated with positivity for (1) immunoglobulin G antibodies (p = 0.009), (2) antihistone antibodies (p = 0.024), and (3) more than one antibody (p = 0.020). Immunoglobulin M antibodies were more common in unmarried than married females (p = 0.020). In contrast, the prevalence of immunoglobulin G antibodies was increased in married women, although differences did not reach statistical significance (p = 0.167). Gravidity and history of fetal loss were not associated with increased antibody positivity. In subjects in whom follow-up data were available, positive antibody titers were not associated with subsequent adverse pregnancy outcome. CONCLUSIONS: In this population autoantibodies are not associated with adverse pregnancy outcome. However, an increased prevalence of immunoglobulin M in unmarried women and immunoglobulin G in married women suggests that a switch from immunoglobulin M to immunoglobulin G autoantibodies is associated with marriage, as a result of either exposure to semen or trophoblast antigens.
Adult↗
Public attitudes about the use of chronological age as a criterion for allocating health care resources.
We present the first systematic national survey of public opinion on age-based rationing of health care resources. Older people were oversampled in order to allow more precise comparisons of attitude by age cohort as well as by other demographic variables. We found that the majority of people accept the withholding of life-prolonging medical care to hopelessly ill patients, but few would categorically withhold such care on the basis of age. The majority of all ages felt that it was the duty of individual patients regardless of age to refuse medical care that is likely to be futile.
Adolescent↗
Corticosteroid treatment for inflammatory bowel disease in pediatric patients increases intraocular pressure.
Intraocular pressure (IOP) was measured in 54 pediatric patients (aged 7-21 years) with inflammatory bowel disease (IBD) who were treated with oral prednisone for 1-104 months. The difference in mean IOP between the treated patients (mean +/- SD, 15.62 +/- 4.11 mm Hg) and 55 age-matched controls (13.83 +/- 2.42 mm Hg) was statistically significant (P = 0.007). The IBD patients were classified as group I, IOP less than or equal to 19 mm Hg in both eyes, and group II, IOP greater than or equal to 20 mm Hg in either eye. Twelve of the 54 patients (22.2%) and none of the controls had IOP greater than or equal to 20 mm Hg (P less than 0.001). Seventeen of the 54 patients (31.5%) were characterized as "steroid responders" (IOP of greater than or equal to 20 mm Hg, change in IOP of greater than or equal to 6 mm Hg between visits, or difference in IOP of greater than or equal to 6 mm Hg between the two eyes). When the dose of prednisone was reduced to 0-10 mg/day 30 days or more before measurement, 9 steroid responders showed a decrease in IOP to within 2 SD of the mean control IOP; 7 of the 9 showed a decrease in IOP of greater than or equal to 6 mm Hg. These observations indicate that while prednisone is a causative factor in increasing the IOP, susceptibility to average doses of prednisone is highly variable, and patients need to be monitored on an individual basis. Because IBD is a chronic disorder that requires prolonged corticosteroid treatment, these children are at risk of developing steroid-induced glaucoma. Careful ophthalmologic monitoring of pediatric IBD patients, as well as of other pediatric patients who receive corticosteroid therapy, is recommended.
Adolescent↗
The interaction of 5-fluorouracil, hydroxyurea, and radiation in two human head and neck cancer cell lines.
We have investigated the effects of 5-fluorouracil (5-FU) and hydroxyurea (HU) with radiation on two human head and neck squamous carcinoma cell lines. SQ-20B has a D0 of 239 cGy and an S phase fraction of 37%, while SQ-38 has a D0 of 146 cGy and an S phase fraction of 31%. For SQ-20B the surviving fraction at 100 cGy was significantly reduced (p < 0.05) when cells were exposed to HU or to 5-FU or both chemotherapy agents together with radiation. No significant effect was seen for SQ-38 with either chemotherapy agent alone or in combination with radiation as compared with radiation alone. Therefore, additive cytotoxicity between 5-FU and HU and radiotherapy was observed only in a head and neck cancer cell line with a higher D0 and a higher S phase fraction.
Cell Survival↗