Optimized dynamic rotation with wedges.

Dynamic rotation is a computer-controlled therapy technique utilizing an automated multileaf collimator in which the radiation beam shape changes dynamically as the treatment machine rotates about the patient so that at each instant the beam shape matches the projected shape of the target volume. In simple dynamic rotation, the dose rate remains constant during rotation. For optimized dynamic rotation, the dose rate is varied as a function of gantry angle. Optimum dose rate at each gantry angle is computed by linear programming. Wedges can be included in the optimized dynamic rotation therapy by using additional rotations. Simple and optimized dynamic rotation treatment plans, with and without wedges, for a pancreatic tumor have been compared using optimization cost function values, normal tissue complication probabilities, and positive difference statistic values. For planning purposes, a continuous rotation is approximated by static beams at a number of gantry angles equally spaced about the patient. In theory, the quality of optimized treatment planning solutions should improve as the number of static beams increases. The addition of wedges should further improve dose distributions. For the case studied, no significant improvements were seen for more than 36 beam angles. Open and wedged optimized dynamic rotations were better than simple dynamic rotation, but wedged optimized dynamic rotation showed no definitive improvement over open beam optimized dynamic rotation.     

Epidemiology of hepatitis B in eastern Kenya

A cross-sectional survey of outpatients attending the three distinct hospitals in the towns of Mombasa, Kilifi, and Malindi was conducted to determine the patterns of hepatitis B transmission in eastern Kenya. Of 1,533 study subjects (mean age 21.9 +/- 13.2 years; range, 4 months to 80 years), 11.4% were positive for HBsAg and 56.2% were seropositive for at least one hepatitis B marker (HBsAg, anti-HBs, or anti-HBc). Anti-delta antibody was found in 1.2% of HBsAg-positive samples. HBeAg was found in 36.0% of HBsAg-positive samples obtained from women of childbearing age. The prevalence of seropositivity for hepatitis B markers was positively correlated with age, increasing from 20% in subjects less than 4 years old to more than 80% in study subjects greater than 40 years old. On multivariate analysis, male sex was found to be associated with HBsAg positivity, and age and previous deliveries of children were associated with seropositivity for any hepatitis marker (HBsAg, anti-HBs, or anti-HBc). An effective hepatitis B immunization strategy in this region of Kenya would require vaccination early in life because a major portion of hepatitis B transmission occurs in childhood.     

Detecting Candida albicans in human milk

Procedures for diagnosis of mammary candidosis, including laboratory confirmation, are not well defined. Lactoferrin present in human milk can inhibit growth of Candida albicans, thereby limiting the ability to detect yeast infections. The inhibitory effect of various lactoferrin concentrations on the growth of C. albicans in whole human milk was studied. The addition of iron to the milk led to a two- to threefold increase in cell counts when milk contained 3.0 mg of lactoferrin/ml and markedly reduced the likelihood of false-negative culture results. This method may provide the necessary objective support needed for diagnosis of mammary candidosis.     

Stages of change for increasing fruit and vegetable consumption among adults and young adults participating in the national 5-a-Day for Better Health community studies.

Higher fruit and vegetable consumption is associated with a reduced risk of certain cancers and chronic diseases. The 5-a-Day for Better Health community studies are evaluating population-based strategies to achieving dietary behavior change using the stages-of-change model and associated theories. The authors present baseline comparisons of stages of change for fruit and vegetable consumption among adults and young adults in eight study sites representing diverse regions of the United States and diverse populations and settings. Three dominant stages, precontemplation, preparation, and maintenance, were found across sites. Women and those with college degrees were more likely to be in action/maintenance. Fruit and vegetable consumption, self-efficacy, and knowledge of the 5-a-Day recommendation were positively associated with more advanced stages of change in all study sites. The authors discuss the findings in relation to possible limitations of this and other dietary stages-of-change measures and suggest directions for future research.     

Marked suppression of dihydrotestosterone in men with benign prostatic hyperplasia by dutasteride, a dual 5alpha-reductase inhibitor

Dihydrotestosterone (DHT) is the primary metabolite of testosterone in the prostate and skin. Testosterone is converted to DHT by 5alpha-reductase, which exists in two isoenzyme forms (types 1 and 2). DHT is associated with development of benign prostatic hyperplasia (BPH), and reduction in its level with 5alpha-reductase inhibitors improves the symptoms associated with BPH and reduces the risk of acute urinary retention and prostate surgery. A selective inhibitor of the type 2 isoenzyme (finasteride) has been shown to decrease serum DHT by about 70%. We hypothesized that inhibition of both isoenzymes with the dual inhibitor dutasteride would more effectively suppress serum DHT levels than selective inhibition of only the type 2 isoenzyme. A total of 399 patients with BPH were randomized to receive once-daily dosing for 24 wk of dutasteride (0.01, 0.05, 0.5, 2.5, or 5.0 mg), 5 mg finasteride, or placebo. The mean percent decrease in DHT was 98.4 +/- 1.2% with 5.0 mg dutasteride and 94.7 +/- 3.3% with 0.5 mg dutasteride, significantly lower (P < 0.001) and with less variability than the 70.8 +/- 18.3% suppression observed with 5 mg finasteride. Mean testosterone levels increased but remained in the normal range for all treatment groups. Dutasteride appeared to be well tolerated with an adverse event profile similar to placebo.     

The effect of a low fat diet on estrogen metabolism

Women who consume a diet low in fat are at lower risk for breast cancer than women whose diet is relatively high in fat. To investigate the effects of a low fat diet on estrogen metabolism, six normal young women were studied while eating a Western-style high fat diet and again after 2 months of consuming a defined low fat diet. Both studies involved the simultaneous administration of [3H]estradiol [( 3H]E2) orally and [14C]E2 iv and the subsequent collection of multiple blood samples and urine for 96 h. The blood samples were analyzed for radioactivity as estrone (E1), E2, their glucuronides, and E1 sulfate. An aliquot of the pooled 96-h urine was analyzed for radioactivity as the glucuronides and sulfates of E1, E2, estriol, 16 alpha-hydroxyestrone (16 alpha-OHE1), and the catechol estrogens, i.e. 2-hydroxy and 2-methoxy metabolites of E1 and E2. The low fat diet resulted in a consistent and significant (P less than 0.05) decrease in urinary excretion of both 16-hydroxylated metabolites, estriol and 16 alpha-OHE1, expressed as a percentage of administered dose of [3H]E2 and [14C]E2, and an increase in the excretion of the catechol estrogens. These changes in metabolite excretion were not, however, mirrored by changes in the MCRs or conversion ratios of either [3H]E2 or [14C]E2. Thus, while neither the clearance of E2 from the blood nor its absorption from the intestinal tract was altered by a relatively short term decrease in dietary fat, there was a shift in the pattern of urinary metabolites away from the purported carcinogenic estrogen (16 alpha-OHE1) and toward the less active catechol estrogens. This may represent an important mechanism whereby low fat diets decrease the risk of breast cancer.