Characterization of speckle in lung images acquired with a benchtop in-line x-ray phase-contrast system.

We investigate the manifestation of speckle in propagation-based x-ray phase-contrast imaging of mouse lungs in situ by use of a benchtop imager. The key contributions of the work are the demonstration that lung speckle can be observed by use of a benchtop imaging system employing a polychromatic tube-source and a systematic experimental investigation of how the texture of the speckle pattern depends on the parameters of the imaging system. Our analyses consists of image texture characterization based on the statistical properties of pixel intensity values.

SU-E-J-05: Validation of an Iterative Tomosynthesis Algorithm for Low Dose on Board Cone Beam CT Patient Localization.

PURPOSE: Cone beam CT (CBCT) is a well established technique to localize patients using bone and soft tissue anatomy. Current protocols are limited to one weekly CBCT due to the considerable imaging dose delivered to the patient. The purpose of this project is to develop and validate a low dose CBCT algorithm to reduce dose and imaging time of current 3D imaging localization procedures using a novel iterative tomosynthesis algorithm to allow daily CBCT for patient positioning and target localization. METHODS: The algorithm is based on the combination of a tomosynthesis filtered back propagation (TFBP) acquisition geometry algorithm and a maximum likelihood expectation maximization (MLEM) iterative reconstruction. Circular or arc acquisition trajectory, projection number, and angular projection position are optimized according to the anatomical treatment site and region of interest. The TFBP method provides the first 3D image estimate, and the MLEM improves its quality. In this study, we focused on head and neck treatment localization imaging. RESULTS: We studied the performance of our tomosynthesis algorithm imaging resolution on an anthropomorphic head and neck phantom to determine image quality as a function of dose reduction techniques. Reconstructed anatomy shows that a 1/8 dose reduction provides similar image quality and resolution as current CBCT protocols. Seven iterations show an optimal compromise between image quality and reconstruction time. Tomosynthesis images provide digitally reconstructed radiographs with similar resolution and contrast as full CBCT. We verified that the iterative process eliminates phantom images originated by the acquired sparse angular data projections. CONCLUSIONS: We developed and validated an iterative algorithm for low dose cone beam CT based on circular or arc tomosynthesis geometries and iterative reconstruction techniques. The algorithm combines the strengths of both techniques to provide a novel low dose method to image patient anatomy for patient positioning and target localization.

SU-E-T-159: Sensitivity of in Line Real Time Scintillating Fiber Detectors for External Beam Treatment Verification and Patient Safety.

PURPOSE: We studied the sensitivity of a novel transmission fiber scintillator array designed and built for in line treatment verification. The purpose of this project is to assess the capability of the fiber detector array technology to detect treatment errors in real time without false positives to enhance patient safety. METHODS: We developed a linear scintillator array detector using radiation hard scintillating fibers and high speed parallel signal conditioning and data acquisition to monitor external beam treatment fluence in real time. The detector captures and resolves the time and amplitude of each linac pulse at each MLC segment. The detector has 60 fibers aligned to each MLC leaf and two output channels per fiber. The data is captured by a high speed parallel digitizer to determine the IMRT beam output delivered to a patient in real time. We evaluated the detector peak pulse linearity according to dose rate, MLC positioning, and beam energy. We analyzed the detector sensitivity, signal to noise ratio, and pulse distribution statistics to determine beam output and fluence in real time. RESULTS: We analyzed the response of the detector to 6 MV and 10 MV photon beams. The statistical analysis of the detected linac pulses indicates that a minimum of 20 pulses are required to evaluate MLC positioning and fluence with 3 mm and 3% resolution, respectively. During testing, no false positives were detected. Linearity with respect to output rate, MLC or jaw opening, and fluence is within 2%. CONCLUSIONS: Measured sensitivity and signal to noise ratio of a real time linear fiber array detector show that delivered beam fluence can be monitored every 55 msec, with no observed false positives during treatment to provide in vivo real time patient safety and beam monitoring.

Mapping genomic regions associated with growth rate in pigs.

The objective of this study was to identify genomic regions associated with postweaning average daily gain (ADG) in swine. Two families were produced using sires obtained from the cross of lines divergently selected for high and low growth rate. Sires were mated to 29 unrelated dams that produced 124 and 115 offspring. Average daily gain was recorded for every individual; mean ADG was .593 +/- .007 kg/d and .619 +/- .009 kg/d in the two families. Selective genotyping was performed as a prescreening procedure to identify genomic regions potentially associated with ADG. A total of 75 genetic markers were used between both families. Markers identified as nominally significant (P < .05) in an individual marker analysis were subsequently typed in all individuals. Markers still nominally significant (P < .05) after analysis with the complete family were then reevaluated together with flanking markers in an interval mapping analysis. A single region on chromosome 3, flanked by markers Sw2429 and Sw251, for the second family had a logarithm of the odds score of 2.9, which is suggestive of linkage with a quantitative trait locus for ADG. Differences were .033 +/- .009 kg/d between individuals inheriting alternative paternal alleles for Sw251, which was the most significant marker.

Relationship of growth hormone and insulin-like growth factor-1 genotypes with growth and carcass traits in swine.

The contribution of chromosomal regions linked to growth hormone (GH) and insulin-like growth factor-1 (IGF-1) loci to variation in preweaning average daily gain, postweaning average daily gain (ADG), 10th rib backfat, loin-eye area and muscle pH were evaluated. Offspring of four purebred sires (A-D; n = 150, 195, 148 and 136, respectively) and two cross-bred sires (E and F; n = 157 and 145, respectively) were genotyped initially with GH and IGF-1 markers. When results of single marker analysis suggested possible linkage with a quantitative trait locus (QTL), additional flanking markers were typed for the family and interval mapping was performed. Growth hormone genotype was not associated with the traits evaluated in the study. Evidence suggestive of linkage was found for IGF-1 genotype and ADG in one sire family (lod = 2.3) where differences were 0.032 +/- 0.01 kg/day for alternative sire alleles. Evidence for a putative ADG QTL was greatest in the interval between IGF-1 and Sw1071. A similar genomic region has been associated with growth variation in mice; however, QTL mapping precision in the current study is insufficient to establish similarity.

Effect of accelerated postpubertal growth and early calving on lactation performance of primiparous Holstein heifers.

Seventy postpubertal Holstein replacement heifers were assigned to one of four treatments to assess effects of accelerated postpubertal growth on performance during first lactation. Heifers were fed control or accelerated diets from 10 mo of age until parturition, and breeding was initiated at 14 or 10 mo of age, respectively. Heifers were also subdivided into two breeding groups (target or delayed) based on normal AI breeding efficiencies. Heifers fed accelerated diets had a higher average daily gain (933 vs. 778 g/d) and calved earlier (21.7 vs. 24.6 mo) than did heifers fed control diets. Heifers fed accelerated diets had similar prepartum (10 d) BW, but lower wither height and postpartum BW, than heifers fed the control. For heifers fed accelerated diets, milk fat and milk protein yields were lower, and milk fat percentage was higher, at mo 1 and 2; milk fat percentage was lower at mo 3 to 7 of lactation. Delayed bred heifers calved later (approximately 2 mo), had higher prepartum and postpartum BW, and were taller at the withers than target bred heifers. Delayed breeding resulted in higher body condition scores at calving and a greater incidence of dystocia, but lactation performance was not affected. Accelerated postpubertal growth resulted in earlier calving at similar prepartum BW, but data for wither height, pelvic area, and postpartum BW suggested that heifers fed accelerated diets were smaller. Accelerated postpubertal growth and early calving reduced performance during first lactation, but the exact mechanisms could not be determined.

Hydro-therapy in CAPD training.

Exercise has been identified as being one of the five most important principles in renal rehabilitation (1). It is well recognised that physical exercise enhances the patients' ability to carry out normal daily activities such as walking, climbing stairs, pursuing gardening or other hobbies and holding employment (1).

High density lipoprotein cholesterol concentration as a predictor of coronary heart disease in West Indian men.

STUDY OBJECTIVE: The aim of the study was to determine whether the inverse association between high density lipoprotein cholesterol concentration and risk of coronary heart disease described in people of European stock was also present in other racial groups. DESIGN: The study was a prospective population survey. Cardiovascular risk factors were examined, including fasting serum lipid estimation (obtained at recruitment). SETTING: This was a community based study within a defined survey area in Trinidad. PARTICIPANTS: All men aged between 35 and 69 years within the survey area were identified and followed between 1977 and 1986. Analysis was confined to those of African, Asian Indian, and mixed descent who were free of coronary heart disease at entry (n = 960, 69% of age eligible men in the survey population). MEASUREMENTS AND MAIN RESULTS: 64 men developed coronary heart disease during the study period. A strong inverse curvilinear relation was found between high density lipoprotein cholesterol and coronary heart disease incidence (p less than 0.005), independent of age or other relevant characteristics including low density lipoprotein cholesterol. CONCLUSIONS: A low serum concentration of high density lipoprotein cholesterol is a risk factor for coronary heart disease in non-whites as well as in whites.

Ethnicity and other characteristics predictive of coronary heart disease in a developing community: principal results of the St James Survey, Trinidad.

A ten-year community survey was undertaken to investigate the high coronary heart disease (CHD) incidence among people of Indian (South Asian) descent in Trinidad, West Indies. Of 2491 individuals aged 35-69 years, 2215 (89%) were examined and 2069 (83%) found to be clinically free of CHD at baseline. After exclusion of 71 of minority ethnic groups, 786 African, 598 Indian, 147 European and 467 adults of Mixed descent were followed for CHD morbidity and mortality. In both sexes, adults of Indian origin had higher prevalence rates of diabetes mellitus, a low concentration of high-density lipoprotein (HDL) cholesterol, and recent abstinence from alcohol than other ethnic groups. Indian men also had larger skinfold thicknesses than other men. In participants free of CHD at entry, the age-adjusted relative risk of a cardiac event believed due to CHD was at least twice as high in Indian men and women as in other ethnic groups. In men, blood pressure, diabetes mellitus and low-density lipoprotein (LDL) cholesterol concentration were positively and independently related to risk of CHD, whereas alcohol consumption and HDL cholesterol concentration were inversely associated with risk after allowing for age and ethnic group. The ethnic contrasts in CHD persisted when these characteristics were taken into account. In the smaller sample of women, only ethnic group was predictive of CHD as defined. The failure of point estimates of risk to explain the high CHD incidence in Indians calls for focus on age of onset of risk and examination of other potential risk factors such as insulin concentration.

Are plasma lipoprotein cholesteryl esters utilized for biliary cholesterol and bile acid production in man?

Studies were carried out to determine whether or not plasma lipoprotein cholesteryl esters are available to the liver for biliary cholesterol and bile acid production in humans with intact biliary tracts. Six healthy males were given intravenous infusions of autologous high-density (d, 1.063-1.21; n = 2), low-density (d, 1.019-1.063; n = 2) or intermediate-density (d, 1.006-1.019; n = 2) lipoproteins that had been labelled in vitro with radioactive cholesteryl linoleate (n = 5) or cholesteryl oleate (n = 1). Duodenal contents were continuously aspirated via the intermediate and distal ports of a triple-lumen tube (mean recovery, 64 per cent), through the proximal port of which was infused an amino-acid solution. During 5-6 hours only moderate fluctuations were observed in bile acid and cholesterol secretion rates, implying the existence of near steady-state conditions. In all subjects radioactivity rapidly appeared in both biliary cholesterol and bile acids, and continued to be secreted for the duration of the experiment. The total radioactivity recovered from cholesterol averaged 0.27 per cent of the administered dose; the corresponding figure for bile acids was 11.2 per cent. These results indicate that lipoprotein cholesteryl esters are readily available for biliary lipid production in humans.

Serum high density lipoprotein subclasses, testosterone and sex-hormone-binding globulin in Trinidadian men of African and Indian descent.

Serum high-density lipoprotein (HDL) cholesterol, testosterone and sex-hormone-binding globulin (SHBG) were measured in 300 men, aged 35-64 years, of African and Indian descent who represented a 40% sample of participants in a community survey of coronary heart disease in Trinidad. Free testosterone was calculated from total testosterone and SHBG. In 113 men, HDL2 and HDL3 cholesterol were measured by a precipitation technique. Indian men had a significantly lower HDL-cholesterol concentration than African men (P = 0.003), which is known to be due to a reduction in the HDL3 fraction (demonstrable only in younger men in the subsample drawn for this study). Testosterone did not differ with ethnic group, but SHBG was reduced in Indians (P = 0.03). After allowance for age, ethnic group, alcohol consumption and smoking habit, HDL cholesterol was associated positively with SHBG (P = 0.025) but was not related significantly to either total testosterone or its free and bound components. Serum HDL2 cholesterol was associated positively and independently with SHBG (P = 0.001) and total and bound testosterone (P = 0.002), whereas HDL3 cholesterol showed no significant associations with these factors. Neither SHBG or testosterone afforded an explanation for the relatively low HDL and HDL3 cholesterol concentrations in Indian men.

An alternative procedure for incorporating radiolabelled cholesteryl ester into human plasma lipoproteins in vitro.

A simple method has been developed for labelling human plasma lipoproteins to high specific radioactivity with radioactive cholesteryl esters in vitro. After isolation by preparative ultracentrifugation, the selected lipoprotein was incubated for 30 min at 4 degrees C in human serum (d greater than 1.215) that had been prelabelled with [4-14C]cholesteryl oleate or [1,2-3H]cholesteryl linoleate, and was then re-isolated by ultracentrifugation. All major lipoprotein classes were labelled by the procedure. Specific radioactivities of up to 18 d.p.m. . pmol-1 (46 d.p.m. . ng-1) were achieved. When radiolabelled high-density lipoprotein was infused intravenously, the radioactive cholesteryl ester behaved in vivo indistinguishably from endogenous cholesteryl esters produced by the lecithin (phosphatidylcholine): cholesterol acyltransferase reaction.

Obesity in women in an urban Trinidadian community. Prevalence and associated characteristics.

Triceps skinfold, body mass index (BMI), blood pressure, blood glucose concentration and serum lipoprotein concentrations were measured in 590 (80 percent) of 738 women aged 35-69 years resident within a defined area of Port-of-Spain, Trinidad. A triceps skinfold of 32 mm or more (the 70th percentile of overall distribution) was found in 36 percent of women of African descent and 28 percent of women of other ethnic origin. Respective figures for a BMI of 30.0 kg/m2 or more were 32 percent and 27 percent at ages 40 to 64 years. Obesity was associated with an increase in blood pressure, increased fasting blood glucose, LDL cholesterol and VLDL triglyceride concentrations, and a reduction in HDL cholesterol concentration. Obese women had an increased tendency to a history of early menarche, multiparity and children of high birthweight. These findings suggested that, irrespective of ethnic origins, the effects of obesity on health in this female population resembled those in white N. American women.

Serum lipoprotein concentrations in relation to ethnic composition and urbanization in men and women of Trinidad, West Indies.

A total population survey of serum lipoprotein concentrations was undertaken in an urban community in Port-of-Spain, Trinidad, and the results compared with rural survey on the same island and a study of healthy adults in Bristol, England. Lipoproteins were separated with identical techniques and lipid determinations made in a common laboratory. In Trinidad, response rates for men and women were 93 and 88% respectively in the urban survey, and 89% in the smaller rural study. Mean concentration of HDL cholesterol was significantly lower and LDL cholesterol significantly higher in urban men than rural men. No urban-rural differences were found in women. In urban men under 55 years, HDL and LDL cholesterol concentrations were similar in Port-of-Spain and Bristol while VLDL triglyceride was relatively high in Trinidad. Distinct ethnic differences in lipoprotein concentrations were found in Trinidad. Indian men and women tended to have a low HDL cholesterol relative to other ethnic groups, while African men and women were characterized by relatively low concentrations of LDL cholesterol and VLDL triglyceride. The reduction in HDL cholesterol of Indian men appeared to be due mainly to a relatively low HDL3 concentration. The results are consistent with reported regional, sex and ethnic differences in CHD incidence in Trinidad, and accord with statistics which show cardiovascular disease to have emerged as the major cause of death in this community.

Serum lipoprotein concentrations in relation to ethnic composition and urbanization in men and women of Trinidad, West Indies

A total population survey of serum lipoprotein concentrations was undertaken in an urban community in Port of Spain, Trinidad, and the results compared with a rural survey on the same island and a study of healthy adults in Bristol, England. Lipoproteins were separated with identical techniques and lipid determinations made in a common laboratory. In Trinidad, response rates for men and women were 93 and 88 percent respectively in the urban survey, and 89percent in the smaller rural study. Mean concentration of HDL cholesterol was significantly lower and LDL cholesterol significantly higher in urban men than rural men. No urban-rural difference were found in women. In urban men under 55 years, HDL and LDL cholesterol concentrations were similar in Port of Spain and Bristol while VLDL triglyceride was relatively high in Trinidad. Distinct ethnic differences in lipoprotein concentrations were found in Trinidad. Indian men and women tended to have a low HDL cholesterol relative to other ethnic groups, while African men and women were characterized by relatively low concentrations of LDL cholesterol and VLDL triglyceride. The reduction in HDL cholesterol in Indian men appeared to be due mainly to a relatively low HDL3 concentration. The results are consistent with reported regional, sex and ethnic differences in CHD incidence in Trinidad, and accord with statistics which show cardiovascular disease to have emerged as the major cause of death in this community

Serum lipoproteins and susceptibility of men of Indian descent to coronary heart disease. The St James Survey, Trinidad.

Prevalence of coronary heart disease (CHD) and fasting serum lipoprotein concentrations in ethnic groups in Port of Spain, Trinidad, were compared. In a total community survey of 1416 men aged 35-69 years, angina pectoris, a history of possible myocardial infarction, and major Q waves on the electrocardiogram were significantly more common in men of Indian descent than in other ethnic groups (relative risk about 3/1). Indians had significantly lower high-density-lipoprotein-cholesterol (HDLCh) concentrations and significantly higher low-density-lipoprotein-cholesterol (LDLCh) concentrations than other groups. After allowance for age and ethnic group, men with major Q waves or a history of possible myocardial infarction had a significantly greater ratio of LDLCh/HDLCh that men without either. Comparison of surveys in the Caribbean suggests that in this region CHD is prevalent only in communities in which a sizeable proportion of men have an LDHCh/HDLCh ratio greater than 6 and an LDLCh concentration above 5 mmol/l.