Using an EPID for patient-specific VMAT quality assurance.

PURPOSE: A patient-specific quality assurance (QA) method was developed to verify gantry-specific individual multileaf collimator (MLC) apertures (control points) in volumetric modulated arc therapy (VMAT) plans using an electronic portal imaging device (EPID). METHODS: VMAT treatment plans were generated in an Eclipse treatment planning system (TPS). DICOM images from a Varian EPID (aS1000) acquired in continuous acquisition mode were used for pretreatment QA. Each cine image file contains the grayscale image of the MLC aperture related to its specific control point and the corresponding gantry angle information. The TPS MLC file of this RapidArc plan contains the leaf positions for all 177 control points (gantry angles). In-house software was developed that interpolates the measured images based on the gantry angle and overlays them with the MLC pattern for all control points. The 38% isointensity line was used to define the edge of the MLC leaves on the portal images. The software generates graphs and tables that provide analysis for the number of mismatched leaf positions for a chosen distance to agreement at each control point and the frequency in which each particular leaf mismatches for the entire arc. RESULTS: Seven patients plans were analyzed using this method. The leaves with the highest mismatched rate were found to be treatment plan dependent. CONCLUSIONS: This in-house software can be used to automatically verify the MLC leaf positions for all control points of VMAT plans using cine images acquired by an EPID.

T-lymphocyte response to H-2 mutants. I. Proliferation is dependent on Ly 1+2+ cells.

We have determined the Ly phenotype of the T lymphocytes which proliferate in response to mutant H-2K and H-2D alloantigens in primary mixed lymphocyte culture. Responder T cells proliferating in reciprocal cultures of H-2d(KdDd) and H-2da(KdDda) lymphocytes were typed Ly 2+ through selective depletion with specific alloantiserum plus complement. Further, B6-Ly 1a lymphocytes proliferating in response to B6-H-2ba and B6-H-2bf stimulators were typed as Ly 1+2+ through similar analysis. These results are discussed with regard to their impact on views of lymphocyte differentiation and factors determining the identity of alloreactive lymphocytes.

Recombinant inbred lines: value in the genetic analysis of biochemical variants.

Analysis of inducibility by androgens and electrophoretic mobility of kidney glucuronidase in progenitor and derived recombinant inbred mouse lines suggests that a single major regulatory gene at or near the glucuronidase structural gene on chromosome 5 determines the rate of enzyme accumulation.

Comparing Visual and Digital Counting Methods to Estimate Horn Fly (Diptera: Muscidae) Populations on Cattle.

Horn fly, Haematobia irritans (L.), population estimates often serve as a diagnostic tool prior to implementing managerial control options available to researchers and producers. Digital photographs taken of cattle infested with horn flies have been suggested to provide similarly accurate population estimates as compared with traditional visual assessments. The objective of this study was to compare visual and digital techniques used to estimate horn fly populations. Sixteen Angus × Hereford yearling heifers artificially infested with four levels of horn flies (Low = 0 flies; Medium = 250 flies; High = 500 flies; Extreme = 1,000 flies) were evaluated. Population estimates were taken visually by experienced (VE1) and inexperienced (VE2) technicians, as well as digitally, with photographs taken on both lateral sides of the south-facing animal. Horn flies were counted in both photographs and combined (CDC) for full body estimates. In addition, the highest photographed side population times two (DDC) was used for comparison. Estimations were made at 0700, 1200, and 1900 h the day following infestation. A time of observation × infestation level interaction (P < 0.01) was detected. On average, VE1 population estimates were greater (P < 0.01) than any other counting method observed. Morning estimates were greater (P < 0.05) than those taken at noon or in the early evening regardless of counting method. Further research regarding the standardization of these techniques to ensure more accurate population estimates is needed before these methods can be incorporated into integrated pest management programs.

Genetics of susceptibility to plasmacytoma induction. I. BALB/cAnN (C), C57BL/6N (B6), C57BL/Ka (BK), (C times B6)F1, (C times BK)F1, and C times B recombinant-inbred strains.

Plasmacytomas were found in 58% of 373 BALB/cAnN (C) mice given three 0.5-ml doses of mineral oil (Bayol F or light mineral oil) or 2,6,10,14-tetramethylpentadecane (pristane) ip. The incidence of plasmacytomas in C57BL/6N (B6), C57BL/Ka (BK), (C times B6)F1 and (C times BK)F1 was 6.4, 0, 11.5, and 16.5%, respectively. The plasmacytomas occurred in old B6 mice, in contrast to their early appearance in strain C mice. The incidence of plasmacytomas in mineral oil-treated or pristane-treated C times B recombinant-inbred (Rl) strain mice was 28.3% in C times BD, 17.5% IN C times BE, 36.5% IN C times BG, 0% in C times BH, 2.9% in C times Bl, 48% in C times BJ, and 4.3% in C times BK. C times BD, C times BG, and C times BJ strains were considered susceptible to plascytoma induction by mineral oil or pristane; C times BE had a low susceptibility, and C times BH, C times Bl, and C times BK were resistant. The results suggested that there were only a few gene difference between C and B6 or BK that determined susceptibility or resistance to plasmacytoma induction, and that B6 and BK have at least one dominant resistance gene. The distribution pattern of susceptibility and resistance in the C times B Rl strains suggested the presence of a resistance gene on chromosome 9, linkage group II.

Genetic analyses of differences in incidence of mammary tumors and reticulum cell neoplasms with the use of recombinant inbred lines of mice.

The influence of genes, in addition to genes in the H-2 complex, that effect the genesis of mammary tumors was studied. The recombinant inbred (RI) CXB lines were chosen for this investigation, because they are well suited for the study of the genetics of a trait for which the genotype affects probability of phenotype expression and which therefore is measured as incidence. Females of seven RI lines (CXBD, CXBE, CXBG, CXBH, CXBI, CXBJ, and CXBK) and their progenitor strains C57BL/6By (B6) and BALB/cBy (BALB/c) were given ip injections of MuMTV at 3 months of age and were force bred. They were observed for mammary tumors. The B6 strain was least susceptible, and mammary tumors appeared late in life. The BALB/c strain was most susceptible, and the tumors appeared early in life. The course of tumor development in the RI lines fell between these extremes. The RI strain distribution pattern of mammary tumor incidence indicated that at least one and probably several loci in addition to those at H-2 determined the difference between the BALB/c and B6 strains. Effects of the other gene(s) appeared to be even more important than those of H-2. The locations of those loci were not made clear by this study. The spontaneous incidence of reticulum cell neoplasms was also recorded. The most frequently formed neoplasm of the reticular system was a Hodgkin's-like lesion. The data suggested an influence of the H-2 complex.

An assay for histocompatibility gene mutations in mice.

A method used for detecting histocompatibility gene mutations by tailskin graft tests in mice is described. Advantages and disadvantages are found for this assay system. The results of published work point to some interesting features of the H-gene mutational event, but also leave many questions yet to be answered.

Further testing of several strains of mice with respect to detection of H - 2 antigens on neonatal erythrocytes.

In previous experiments the existence of two types of neonatal erythrocytes was confirmed in different inbred and congenic strains of mice. Erythrocytes of the "early" type were agglutinable by the appropriate antisera on the day of birth; the "late" type erythrocytes were not agglutinable until the third day of postnatal life. Results of earlier studies on segregating generations supported the proposed "remote-cis-effect" model for genetic control of H-2 antigen detectability in newborns. We report on tests that bear further upon this phenomenon.

Calf production by Angus-Hereford and Brahman-Hereford cows on two native rangeland forage systems.

Calf birth weights, weaning weights, and preweaning gain of Simmental-sired calves from Angus-Hereford (AH) and Brahman-Hereford (BH) F1 cows grazing native rangeland (NR) or native rangeland-complementary forage (NRCF) systems in the southern Great Plains mixed prairie were evaluated. Calves from AH dams were heavier (P < .001) at birth than calves from BH dams in both forage systems (40 and 37 kg, respectively). However, birth weights of calves from BH dams were 2 kg heavier (P < .001) in the NRCF fall-calving system. Calves in the NRCF system were 122 d older and heavier (P < .001) than the NR calves at weaning (343 and 256 kg, respectively). During the preweaning period, the NR calves gained faster (P < .001) than the NRCF calves. When calves from both systems were evaluated at 200 d of age, NR calves were heavier (P < .001) than NRCF calves. Calves from BH cows were 8 to 16 kg heavier (P < .001) that calves from AH cows at 200 d of age and at weaning. The increased age at weaning associated with the NRCF did not reduce reproductive efficiency. The NRCF system requires less land than a traditional NR system to support a cow-calf pair and seems to be more economically efficient.

Relationship between terrain use and performance of beef cows grazing foothill rangeland.

A study was conducted on foothills rangeland to determine whether grazing patterns differed among cow breeds and to determine whether there was a relationship between individual grazing patterns and performance of beef cows. Hereford (HH), Tarentaise (TT), 3/4 Hereford x 1/4 Tarentaise (3H1T), 1/2 Hereford x 1/2 Tarentaise (HT), and 1/4 Hereford x 3/4 Tarentaise (1H3T) cows were observed during the summers of 1997 (n = 183) and 1998 (n = 159). Locations of individual cows were recorded two to three times per week during 1.5- to 2.5-h periods in the morning by observers on horseback. Statistical models included cow breed, age, and nursing status. Data from each year were analyzed separately. During 1997 and 1998, nonlactating cows were located at greater (P < 0.05) vertical distances from water than lactating cows. In 1998, nonlactating cows used steeper (P < 0.05) slopes than lactating cows. However, nonlactating cows did not travel as far horizontally from water (P < 0.05) as lactating cows in 1997. Younger cows (3 yr) traveled further (P < 0.05) from water both vertically and horizontally than older cows (5+ yr) in 1997, but not during 1998. Tarentaise and 1H3T cows were observed at greater (P < 0.05) vertical distances from water than HH cows during both years of the study. During 1998, TT and 1H3T cows used steeper (P < 0.05) slopes than HH cows. Using residual correlations, there were no consistent relationships between topographic aspects of individual grazing locations and cow weight, height, and body condition score. In 1997, cows with earlier calving dates and correspondingly heavier calf weaning weights used areas that had greater vertical distances to water; however, in 1998 there were no relationships (P > 0.05) of calving date and weaning weight with cow location. During both years, pregnant and nonpregnant cows used terrain similarly (P > 0.05), which suggests that cow reproductive performance was not related to terrain use. Grazing patterns in foothills rangeland varied among cow breeds. Performance of cows that used more rugged topography was similar to cows using gentler terrain.

Thinking about thinking.

BACKGROUND: The nursing leadership at a 900-bed tertiary-care facility in the southeast believed an opportunity existed to improve the critical thinking abilities of the professional nursing staff. METHOD: A team, consisting of a diversified group of nurse educators and managers, had the opportunity to gain understanding of the critical thinking process of the nursing staff as well as to develop a plan designed to improve critical thinking skills. RESULTS: Outputs of the team included development of a critical thinking model and process as well as an action plan that specifically outlined how it would implement the model within the organization using a preceptor-based educational process. CONCLUSION: Nursing leadership within this facility believes that nurturing critical thinking in the staff will have a positive impact on care delivery outcomes. Creating shared visions through the assumptions that the staff and organization hold is important to improving care provided. Assisting staff with using a critical thinking process in order to construct, tear down, and then reconstruct clinical incidents as encouraged by this model is one key to problem-solving.

Growth characteristics, reproductive performance, and evaluation of their associative relationships in Brangus cattle managed in a Chihuahuan Desert production system1.

Balancing growth and reproductive performance in beef cattle managed in desert environments is challenging. Our objectives were to 1) evaluate trends in growth and reproductive traits, and 2) assess associative relationships between growth characteristics and reproductive performance in a Brangus herd managed in a Chihuahuan Desert production system from 1972 to 2006. Data were from bull (n = 597) and heifer calves (n = 585; 1988 to 2006) and cows (n = 525; repeated records of cows, n = 2,611; 1972 to 2006). Variables describing the growth curve of each cow were estimated using a nonlinear logistic function (each cow needed 6 yr of data). Mixed-effect models and logistic regression were used to analyze trends across years in growth and reproductive traits (both continuous and categorical). For continuous traits of calves, a slight cubic response (P < 0.01) described the dynamics of birth weight, 205-d BW, and 365-d BW across years. For categorical traits of females, positive linear trends (P < 0.05) across years were observed in percent pregnant as yearlings, calved at 2 yr of age, and first-calf heifer rebreeding (slopes ranged from 0.007 to 0.014%/yr). Autumn cow BW increased gradually until 1997 (509 kg +/- 8.8) and then decreased gradually by 0.6 kg/yr, whereas pregnancy percentage decreased gradually until 1995 (78.4% +/- 1.0) and then increased slightly by 0.2%/yr. A quadratic effect best described the dynamics of these 2 variables across years (P < 0.01) as well as estimates describing the growth curve of each cow. Specifically, asymptotic BW and age increased (P < 0.05) from 1972 to 1983 and 1990, respectively. Asymptotic age then decreased by 27% from 1983 to 1996 (P < 0.05). The maturing rate index was negatively correlated with age at first calving and calving interval (r = -0.42 and -0.18, P < 0.01), which suggested that early-maturing cows had enhanced fertility in this environment and production system. In summary, minimal changes were observed in measures of growth in bulls and heifers in a Brangus herd managed in the Chihuahuan Desert. Opposing relationships were observed among measures of cow size and fertility; as growth curves shifted toward earlier maturity, measures of reproductive performance suggested that fertility improved.