Zinc and multivitamin supplementation have contrasting effects on infant iron status: a randomized, double-blind, placebo-controlled clinical trial

BACKGROUND

Zinc supplementation adversely affects iron status in animal and adult human studies but few, trials have included young infants.

OBJECTIVE

To determine the effects of zinc and multivitamin supplementation on infant hematologic and iron status.

METHODS

In a double-blind RCT, Tanzanian infants were randomized to daily, oral zinc (Zn), multivitamins (MV), Zn and MV, or placebo treatment arms at age 6 wk. Hemoglobin concentration (Hb) and red blood cell indices were measured at baseline and at 6, 12, and 18 mo of age. Plasma samples from 589 infants were examined for iron deficiency (ID) at 6 mo.

RESULTS

In logistic regression models, Zn treatment was associated with greater odds of ID (OR 1.8 [95% CI 1.0–3.3]), and MV treatment was associated with lower odds (OR 0.49 [95% CI 0.3–0.9]). In Cox models, MV were associated with a 28% reduction in risk of severe anemia (HR=0.72 [95% Cl 0.56–0.94]) and a 26% reduction in risk of severe microcytic anemia (HR=0.74 [0.56–0.96]) through 18 months. No effects of Zn on risk of anemia were seen. Infants treated with MV alone had higher mean Hb (9.9 g/dL [95% CI 9.7–10.1]) than those given placebo (9.6 g/dL [9.4–9.8]) or Zn alone (9.6 g/dL [9.4–9.7]).

CONCLUSIONS

MV treatment improved iron status in infancy, whereas Zn worsened iron status but without an associated increase in risk for anemia. Infants in long-term zinc supplementation programs at risk for ID may benefit from screening and/or the addition of a multivitamin supplement.

Prospective cohort study comparing transient EUS guided elastography to EUS-FNA for the diagnosis of solid pancreatic mass lesions

BACKGROUND

Semiquantitative EUS-elastography has been introduced to distinguish between malignant and benign pancreatic lesions. This study investigated whether semiquantitative EUS-guided transient real time elastography increases the diagnostic accuracy for solid pancreatic lesions compared to EUS-FNA.

PATIENTS AND METHODS

This single centre prospective cohort study included all patients with solitary pancreatic lesions on EUS during one year. Patients underwent EUS-FNA and semiquantitative EUS-elastography during the same session. EUS and elastography results were compared with final diagnosis which was made on the basis of tissue samples and long-term outcome.

RESULTS

91 patients were recruited of which 68 had pancreatic malignancy, 17 showed benign disease and 6 had cystic lesions and were excluded from further analysis. Strain ratios from malignant lesions were significantly higher (24.00; 8.01-43.94 95% CI vs 44.00; 32.42-55.00 95% CI) and ROC analysis indicated optimal cut-off of 24.82 with resulting sensitivity, specificity and accuracy of 77%, 65% and 73% respectively. B-mode EUS and EUS-FNA had an accuracy for the correct diagnosis of malignant lesions of 87% and 85%. When lowering the cut-off strain ratio for elastography to 10 the sensitivity rose to 96% with specificity of 43% and accuracy of 84%, resulting in the least accurate EUS-based method. This was confirmed by pairwise comparison.

CONCLUSION

Semiquantitative EUS-elastography does not add substantial value to the EUS-based assessment of solid pancreatic lesions when compared to B-mode imaging.

Cost Effectiveness of a Sugar-Sweetened Beverage Excise Tax in the U.S

INTRODUCTION

Reducing sugar-sweetened beverage consumption through taxation is a promising public health response to the obesity epidemic in the U.S. This study quantifies the expected health and economic benefits of a national sugar-sweetened beverage excise tax of $0.01/ounce over 10 years.

METHODS

A cohort model was used to simulate the impact of the tax on BMI. Assuming ongoing implementation and effect maintenance, quality-adjusted life-years gained and disability-adjusted life-years and healthcare costs averted were estimated over the 2015-2025 period for the 2015 U.S.

POPULATION

Costs and health gains were discounted at 3% annually. Data were analyzed in 2014.

RESULTS

Implementing the tax nationally would cost $51 million in the first year. The tax would reduce sugar-sweetened beverage consumption by 20% and mean BMI by 0.16 (95% uncertainty interval [UI]=0.06, 0.37) units among youth and 0.08 (95% UI=0.03, 0.20) units among adults in the second year for a cost of $3.16 (95% UI=$1.24, $8.14) per BMI unit reduced. From 2015 to 2025, the policy would avert 101,000 disability-adjusted life-years (95% UI=34,800, 249,000); gain 871,000 quality-adjusted life-years (95% UI=342,000, 2,030,000); and result in $23.6 billion (95% UI=$9.33 billion, $54.9 billion) in healthcare cost savings. The tax would generate $12.5 billion in annual revenue (95% UI=$8.92, billion, $14.1 billion).

CONCLUSIONS

The proposed tax could substantially reduce BMI and healthcare expenditures and increase healthy life expectancy. Concerns regarding the potentially regressive tax may be addressed by reduced obesity disparities and progressive earmarking of tax revenue for health promotion.

Cost Effectiveness of Childhood Obesity Interventions: Evidence and Methods for CHOICES

INTRODUCTION

The childhood obesity epidemic continues in the U.S., and fiscal crises are leading policymakers to ask not only whether an intervention works but also whether it offers value for money. However, cost-effectiveness analyses have been limited. This paper discusses methods and outcomes of four childhood obesity interventions: (1) sugar-sweetened beverage excise tax (SSB); (2) eliminating tax subsidy of TV advertising to children (TV AD); (3) early care and education policy change (ECE); and (4) active physical education (Active PE).

METHODS

Cost-effectiveness models of nationwide implementation of interventions were estimated for a simulated cohort representative of the 2015 U.S. population over 10 years (2015-2025). A societal perspective was used; future outcomes were discounted at 3%. Data were analyzed in 2014. Effectiveness, implementation, and equity issues were reviewed.

RESULTS

Population reach varied widely, and cost per BMI change ranged from $1.16 (TV AD) to $401 (Active PE). At 10 years, assuming maintenance of the intervention effect, three interventions would save net costs, with SSB and TV AD saving $55 and $38 for every dollar spent. The SSB intervention would avert disability-adjusted life years, and both SSB and TV AD would increase quality-adjusted life years. Both SSB ($12.5 billion) and TV AD ($80 million) would produce yearly tax revenue.

CONCLUSIONS

The cost effectiveness of these preventive interventions is greater than that seen for published clinical interventions to treat obesity. Cost-effectiveness evaluations of childhood obesity interventions can provide decision makers with information demonstrating best value for the money.

Preliminary analysis of the cost-effectiveness of the National Bowel Cancer Screening Program: demonstrating the potential value of comprehensive real world data

BACKGROUND/AIM

The complexity and cost of treating cancer patients is escalating rapidly and increasingly difficult decisions are being made regarding which interventions provide value for money. BioGrid Australia supports collection and analysis of comprehensive treatment and outcome data across multiple sites. Here, we use preliminary data regarding the National Bowel Cancer Screening Program (NBCSP) and stage-specific treatment costs for colorectal cancer (CRC) to demonstrate the potential value of real world data for cost-effectiveness analyses (CEA).

METHODS

Data regarding the impact of NBCSP on stage at diagnosis were combined with stage-specific CRC treatment costs and existing literature. An incremental CEA was undertaken from a government healthcare perspective, comparing NBCSP with no screening. The 2008 invited population (n= 681,915) was modelled in both scenarios. Effectiveness was expressed as CRC-related life years saved (LYS). Costs and benefits were discounted at 3% per annum.

RESULTS

Over the lifetime and relative to no screening, NBCSP was predicted to save 1265 life years, prevent 225 CRC cases and cost an additional $48.3 million, equivalent to a cost-effectiveness ratio of $38,217 per LYS. A scenario analysis assuming full participation improved this to $23,395.

CONCLUSIONS

This preliminary CEA based largely on contemporary real world data suggests population-based faecal occult blood test screening for CRC is attractive. Planned ongoing data collection will enable repeated analyses over time, using the same methodology in the same patient populations, permitting an accurate analysis of the impact of new therapies and changing practice. Similar CEA using real world data related to other disease types and interventions appears desirable.

Cardiopulmonary exercise testing as a predictor of complications in oesophagogastric cancer surgery

Introduction

An anaerobic threshold (AT) of <11ml/min/kg can identify patients at high risk of cardiopulmonary complications after major surgery. The aim of this study was to assess the value of cardiopulmonary exercise testing (CPET) in predicting cardiopulmonary complications in high risk patients undergoing oesophagogastric cancer resection.

Methods

Between March 2008 and October 2010, 108 patients (83 men, 25 women) with a median age of 66 years (range: 38–84 years) underwent CPET before potentially curative resections for oesophagogastric cancers. Measured CPET variables included AT and maximum oxygen uptake at peak exercise (VO₂ peak). Outcome measures were length of high dependency unit stay, length of hospital stay, unplanned intensive care unit (ICU) admission, and postoperative morbidity and mortality.

Results

The mean AT and VO₂ peak were 10.8ml/min/kg (standard deviation [SD]: 2.8ml/min/kg, range: 4.6–19.3ml/min/kg) and 15.2ml/min/kg (SD: 5.3ml/min/kg, range: 5.4–33.3ml/min/kg) respectively; 57 patients (55%) had an AT of <11ml/min/ kg and 26 (12%) had an AT of <9ml/min/kg. Postoperative complications occurred in 57 patients (29 cardiopulmonary [28%] and 28 non-cardiopulmonary [27%]). Four patients (4%) died in hospital and 21 (20%) required an unplanned ICU admission. Cardiopulmonary complications occurred in 42% of patients with an AT of <9ml/min/kg compared with 29% of patients with an AT of ≥9ml/min/kg but <11ml/min/kg and 20% of patients with an AT of ≥11ml/min/kg (p=0.04). There was a trend that those with an AT of <11ml/min/kg and a low VO₂ peak had a higher rate of unplanned ICU admission.

Conclusions

This study has shown a correlation between AT and the development of cardiopulmonary complications although the discriminatory ability was low.

Cardiopulmonary exercise testing as a predictor of complications in oesophagogastric cancer surgery

Introduction

An anaerobic threshold (AT) of <11ml/min/kg can identify patients at high risk of cardiopulmonary complications after major surgery. The aim of this study was to assess the value of cardiopulmonary exercise testing (CPET) in predicting cardiopulmonary complications in high risk patients undergoing oesophagogastric cancer resection.

Methods

Between March 2008 and October 2010, 108 patients (83 men, 25 women) with a median age of 66 years (range: 38–84 years) underwent CPET before potentially curative resections for oesophagogastric cancers. Measured CPET variables included AT and maximum oxygen uptake at peak exercise (VO2 peak). Outcome measures were length of high dependency unit stay, length of hospital stay, unplanned intensive care unit (ICU) admission, and postoperative morbidity and mortality.

Results

The mean AT and VO2 peak were 10.8ml/min/kg (standard deviation [SD]: 2.8ml/min/kg, range: 4.6–19.3ml/min/kg) and 15.2ml/min/kg (SD: 5.3ml/min/kg, range: 5.4–33.3ml/min/kg) respectively; 57 patients (55%) had an AT of <11ml/min/ kg and 26 (12%) had an AT of <9ml/min/kg. Postoperative complications occurred in 57 patients (29 cardiopulmonary [28%] and 28 non-cardiopulmonary [27%]). Four patients (4%) died in hospital and 21 (20%) required an unplanned ICU admission. Cardiopulmonary complications occurred in 42% of patients with an AT of <9ml/min/kg compared with 29% of patients with an AT of ≥9ml/min/kg but <11ml/min/kg and 20% of patients with an AT of ≥11ml/min/kg (p=0.04). There was a trend that those with an AT of <11ml/min/kg and a low VO2 peak had a higher rate of unplanned ICU admission.

Conclusions

This study has shown a correlation between AT and the development of cardiopulmonary complications although the discriminatory ability was low.

Cardiopulmonary exercise testing as a predictor of complications in oesophagogastric cancer surgery

INTRODUCTION

An anaerobic threshold (AT) of <11 ml/min/kg can identify patients at high risk of cardiopulmonary complications after major surgery. The aim of this study was to assess the value of cardiopulmonary exercise testing (CPET) in predicting cardiopulmonary complications in high risk patients undergoing oesophagogastric cancer resection.

METHODS

Between March 2008 and October 2010, 108 patients (83 men, 25 women) with a median age of 66 years (range: 38-84 years) underwent CPET before potentially curative resections for oesophagogastric cancers. Measured CPET variables included AT and maximum oxygen uptake at peak exercise (VO2 peak). Outcome measures were length of high dependency unit stay, length of hospital stay, unplanned intensive care unit (ICU) admission, and postoperative morbidity and mortality.

RESULTS

The mean AT and VO2 peak were 10.8 ml/min/kg (standard deviation [SD]: 2.8 ml/min/kg, range: 4.6-19.3 ml/min/kg) and 15.2 ml/min/kg (SD: 5.3 ml/min/kg, range: 5.4-33.3 ml/min/kg) respectively; 57 patients (55%) had an AT of <11 ml/min/kg and 26 (12%) had an AT of <9 ml/min/kg. Postoperative complications occurred in 57 patients (29 cardiopulmonary [28%] and 28 non-cardiopulmonary [27%]). Four patients (4%) died in hospital and 21 (20%) required an unplanned ICU admission. Cardiopulmonary complications occurred in 42% of patients with an AT of <9 ml/min/kg compared with 29% of patients with an AT of ≥9 ml/min/kg but <11 ml/min/kg and 20% of patients with an AT of ≥11 ml/min/kg (p = 0.04). There was a trend that those with an AT of <11 ml/min/kg and a low VO2 peak had a higher rate of unplanned ICU admission.

CONCLUSIONS

This study has shown a correlation between AT and the development of cardiopulmonary complications although the discriminatory ability was low.

Long-term follow-up of endoscopic Histoacryl glue injection for the management of gastric variceal bleeding

BACKGROUND

Variceal bleeding is an acute medical emergency with high mortality. Although less common than oesophageal variceal haemorrhage, gastric variceal bleeding is more severe and more difficult to control. The optimal therapy for gastric variceal bleeding remains unclear although endoscopic injection of N-Butyl-2-Cyanoacrylate (Histoacryl) glue is often used. However, its long-term efficacy is poorly described. We studied the immediate and long-term effects of Histoacryl glue injection as treatment for bleeding gastric varices in a large UK hospital.

METHOD

Endoscopy records and case notes were used to identify patients receiving Histoacryl injection for gastric variceal bleeding over a 4-year period.

RESULTS

Thirty-one patients received Histoacryl for gastric variceal bleeding. Seventy-four per cent patients had alcohol-related liver disease and 61% of cirrhotics were Childs Pugh grade B or C. Fifty-eight per cent were actively bleeding during the procedure with 100% haemostasis rates achieved. Two patients developed pyrexia within 24 h of injection settling with antibiotics. No other complications were encountered. Mean overall follow-up was 35 months, with mean follow-up of survivors 57 months. Forty-eight per cent patients had endoscopic ultrasound assessment of varices during follow-up with no effect on rebleeding rates. Thirteen per cent required subsequent transjugular intrahepatic portosystemic shunt placement. Gastric variceal rebleeding rate was 10% at 1 year and 16% in total. One- and two-year mortality was 23% and 35%, respectively.

CONCLUSION

Endoscopic injection of Histoacryl glue appears to be a safe and effective treatment for gastric variceal bleeding. Further data are required to compare it with other therapies in this situation.

An assessment of microbiological water quality of six water source categories in north-east Uganda

Target 7C of the Millennium Development Goals is to "halve, by 2015, the proportion of people without sustainable access to safe drinking water and basic sanitation". However, the corresponding indicator measures the "proportion of population using an improved drinking water source". This raises the question of whether "safe" and "improved" can be used interchangeably. This paper tests this hypothesis by comparing microbiological water quality in 346 different water sources across the District of Amuria in Uganda to each other and to defined standards, including the WHO drinking water standard of zero TTC per 100 ml, and the Ugandan national standard of 50 TTC per 100 ml. The water sources were grouped into six different categories: boreholes, protected springs, covered hand dug wells, open hand dug wells, open water and roofwater harvesting. The paper concludes that the ranking from the highest to the lowest microbiological quality water was: boreholes, protected springs and roofwater harvesting, open and covered hand dug wells, open water. It also concludes that sanitary surveys cannot be used to predict water quality precisely; however they are an essential component of the monitoring of safe water supplies.

Performance Evaluation Tests for Environmental Research (PETER): evaluation of 114 measures

The goal of the Performance Evaluation Tests for Environmental Research (PETER) Program was to identify a set of measures of human capabilities for use in the study of environmental and other time-course effects. 114 measures studied in the PETER Program were evaluated and categorized into four groups based upon task stability and task definition. The Recommended category contained 30 measures that clearly obtained total stabilization and had an acceptable level of reliability efficiency. The Acceptable-But-Redundant category contained 15 measures. The 37 measures in the Marginal category, which included an inordinate number of slope and other derived measures, usually had desirable features which were outweighed by faults. The 32 measures in the Unacceptable category had either differential instability or weak reliability efficiency. It is our opinion that the 30 measures in the Recommended category should be given first consideration for environmental research applications. Further, it is recommended that information pertaining to preexperimental practice requirements and stabilized reliabilities should be utilized in repeated-measures environmental studies.

Ex vivo delineation of placental angioarchitecture with the microbubble contrast agent Levovist

OBJECTIVE

The aim of this study was to delineate placental vasculature with the microbubble contrast agent Levovist (99.9% galactose and 0.1% palmitic acid; Schering AG, Berlin, Germany), with the ultimate goal of delineating placental vascular anatomy in utero.

STUDY DESIGN

A placental lobule from each of 11 term human placentas was perfused on the fetal side of the circulation under physiologic conditions. Randomly assigned dose-concentration combinations of Levovist were administered through a chorionic artery into the corresponding placental lobule, and the resultant echoenhancement with power Doppler imaging was recorded for digital analysis. Interplacental variability was corrected for by averaging the results of three injections at each dose-concentration combination.

RESULTS

Echoenhancement was seen at all dose-concentration combinations in the injected lobule but not in adjacent control lobules. The three dose-concentration combinations that achieved optimal maximal integrated intensity and duration of action for both chorionic vessel and villus enhancement were 100 microL/kg of 400-mg/mL Levovist, 200 microL/kg of 400-mg/mL Levovist, and 400 microL/kg of 200-mg/mL Levovist.

CONCLUSION

Microbubble contrast injection into the fetal vasculature enabled power Doppler imaging echoenhancement both in chorionic vessels and within the villus tree. We speculate that fetal injection of contrast agent may be applied to the delineation of placental lesions or areas of interfetal transfusion, although its applicability will be hindered by the need for fetal blood sampling.

Is phase-specific, community-oriented treatment of early psychosis an economically viable method of improving outcome?

OBJECTIVE

The Early Psychosis Prevention and Intervention Centre (EPPIC) provides a comprehensive 'real-world' model of early intervention to young people experiencing an emerging psychotic disorder. A prospective study has already provided evidence of improved clinical outcome at 12 months after entry. The present study examined whether the service was also cost-effective.

METHOD

A cost-effectiveness analysis compared EPPIC with its immediate precursor service, from the perspective of the government funding agency. Only direct costs were included.

RESULTS

EPPIC proved to be more cost-effective. The weighted average cost per patient for the first 12 months was cheaper (by $AUD 7110 per patient), while treatment outcomes were superior. The savings were due to the marked reduction in in-patient costs outweighing substantial increases in the costs of community care.

CONCLUSION

These results, while encouraging in terms of the further development of integrated, phase-specific intervention programmes for early psychosis, are not conclusive, and further research is required.

Risk factors for seizure-related motor vehicle crashes in patients with epilepsy

OBJECTIVE

We identified clinical risk factors for seizure-related motor vehicle crashes in patients with epilepsy.

BACKGROUND

Current US laws permit epilepsy patients with controlled seizures to drive. These laws attempt to balance the important economic and social value of driving with the risk to public safety from seizure-related crashes. Various clinical factors are considered in these laws, particularly the seizure-free interval. Driving restrictions range from 3 to 18 months, however, and studies have not established how these various seizure-free intervals and other clinical factors influence the risk for seizure-related motor vehicle crashes.

METHODS

We performed a retrospective case-control study to determine the influence of clinical risk factors associated with seizure-related motor vehicle crashes. Both "case" and "control" patients had epilepsy, drove, and were from the same clinic, but the cases differed in having had seizure-related crashes.

RESULTS

Fifty patients with epilepsy who crashed during seizures and 50 matched control patients were compared. Factors that significantly decreased the odds of patients with epilepsy having motor vehicle crashes due to seizures were: long seizure-free intervals, reliable auras, few prior nonseizure-related accidents, and having had their antiepileptic drugs (AEDs) reduced or switched. For example, patients who had seizure-free intervals > or = 12 months had a 93% reduced odds for crashing compared to patients with shorter intervals. Other findings were: 25% of patients had more than one seizure-related crash and 20% had missed an AED dose just prior to their crash. The majority (54%) of patients who crashed were driving illegally, with seizure-free intervals shorter than legally permitted.

CONCLUSION

Seizure-free intervals, the presence of reliable auras, AED therapy modifications, and a history of nonseizure-induced crashes should be considered when counseling patients with epilepsy on driving and when formulating driving regulatory policy. Case control studies of crashes due to seizures can help in assessing and monitoring such risks.

Evaluation of a series of N-alkyl benzomorphans in cell lines expressing transfected delta- and mu-opioid receptors

Transfection of individual opioid receptors in Chinese hamster ovary (CHO) cells provides a pure, homogeneous population of receptors for screening drug candidates, and an alternative to the use of selective ligands. To evaluate the potential of this system, we chose a series of (-)-5,9 alpha-dimethyl-2-hydroxy-N-substituted-6,7-benzomorphans, for which the receptor selectivity and in vivo activity had been characterized recently, and tested them in CHO cells stably transfected with either the rat delta-opioid receptor or the mouse mu-opioid receptor. [3H]Diprenorphine was used to measure opioid receptors in P2 membrane preparations. A Bmax of 7.58 +/- 0.8 pmol/mg protein and a Kd of 0.42 +/- 0.04 nM was obtained in the mu-opioid receptor expressing cell line used in these studies. In addition, [3H]naltrindole was used to confirm the delta-specificity of the cloned receptor. Both compounds gave a Bmax of 1.2 pmol/mg in the CHO cells expressing the rat delta-opioid receptor. Displacement assays were performed with eleven (-)-N-alkyl-benzomorphans in the absence and presence of 150 mM NaCl, as well as known delta- and mu-selective agonists. Sodium reduced agonist affinity in the transfected cell lines. The benzomorphan compounds displayed a range of affinities in the mu- and delta-opioid receptor expressing cell lines. Good correlations were found between their affinities at the cloned mu- and delta-opioid receptors and those in rat brain and monkey cortex (r2 from 0.73 to 0.89, P < 0.001). Comparative analysis of Ki values with in vivo potency in the mouse tail flick test indicated a high degree of correlation between antinociception and affinity in the mu-opioid receptor cell line (r2 = 0.83, p < 0.0001). Lesser correlations were found between antinociception in the mouse and affinity at the rat mu-opioid receptor (r2 = 0.6610) and at the monkey mu-opioid receptor (r2 = 0.695). In sum, these studies indicate that the cell lines expressing the cloned mu- and delta-opioid receptors are appropriate models for determining the binding affinities of this class of opioid compounds. The diminishing correlations found between species when comparing in vitro and in vivo activity suggest that caution should be taken when extrapolating binding data to pharmacological activity among species.

Performance Evaluation Tests for Environmental Research (PETER): Moran and computer batteries

This investigation was directed at evaluating nine cognitive ability tasks for repeated measures applications and inclusion in the Performance Evaluation Tests for Environmental Research (PETER) battery. In the first study, five tasks from the Moran Battery, which were adapted from the French kit of factor-referenced tests, were administered to 18 subjects daily for 13 workdays. In the second study, four tasks from the Carter and Sbisa Computer Generated Battery were administered daily to 17 subjects (12 in common with first study) for 15 workdays. Examination of the means, variances, and interday reliabilities, together with factor analysis of the cross-task correlations, led to the recommendation of four tasks. Tasks recommended for repeated measures applications were Vertical Addition, Perceptual Speed, Grammatical Reasoning, and Flexibility of Closure.

High-contrast sets of colors

A method is presented for choosing high-contrast sets of colors for additive color mixers (e.g., CRT). The method is based on data about target-location performance of human observers and adapts the color sets to the gamut of the color processor in use. The method produces any specified number of colors spread as far from each other as possible in color space to maximize contrast. Applications of high-contrast sets of colors are indicated, illustrative results are presented and discussed, and variations of the method are suggested.

Visual search with color

Three experiments were conducted to discover how rapidly people can find a particular target when they know the color of the target. The subjects searched for specific-colored three-digit numbers among other three-digit numbers on a circular display screen. Three factors had profound effects on search speed. Search time increased dramatically (and approximately linearly) as the number of display items of the target's color increased from one to all of the items on the display. Search time also increased with the number of items not of the target's color (background items), if the color of those background items was sufficiently similar to that of the target. If the color of those background items was dissimilar to that of the target, then the background items had no effect. An effect of patterned versus random placement of target-colored items was also demonstrated.

Search time with a color display: analysis of distribution functions

Color displays were used for a search task. The task involved locating a particular three-digit number in a background of other numbers, given the first two digits of the target and its color. The display variables were the number of display items of the same color as the target (TCS); the number of background items not of the target's color (NOB); and the color difference between the target and background items (ΔE). Search times obtained with each of 17 combinations of these conditions were discussed in terms of their cumulative distribution functions (CDFs). The observed CDFs were compared with some theoretical CDFs: normal, linear, and exponential. Search times were normally distributed when targets were immediately obvious to searchers (TCS and NOB small,ΔE large). The exponential CDF was best when the target was less conspicuous (TCS and NOB large, ΔE small) so that searchers had to scan the display to locate the target. The exponential model was improved by addition of a parameter to represent human response time. Furthermore, the parameters of the exponential model were shown to respond in a consistent and theoretically meaningful manner to changes of the display variables.

Visual search with color

Three experiments were conducted to discover how rapidly people can find a particular target when they know the color of the target. The subjects searched for specific-colored three-digit numbers among other three-digit numbers on a circular display screen. Three factors had profound effects on search speed. Search time increased dramatically (and approximately linearly) as the number of display items of the target's color increased from one to all of the items on the display. Search time also increased with the number of items not of the target's color (background items), if the color of those background items was sufficiently similar to that of the target. If the color of those background items was dissimilar to that of the target, then the background items had no effect. An effect of patterned versus random placement of target-colored items was also demonstrated.

Color and conspicuousness

The principle that things are easier to find if they contrast with their environment is expressed quantitatively. Two indices of conspicuousness, relative fixation rate and search time, are shown to be related to the color difference between the target and background objects. The color difference equations used are CIELAB, CIELUV, and the Judd modification of the index of fading. None of the equations is superior to the others. Furthermore, neither Judd's modification nor Semmelroth's adjustment accounts for effects of surround lightness. It is suggested that color difference be used as a tool for design and evaluation of visual displays, for construction of color codes to optimize search time, and as a generalization of chromatic contrast in psychophysical research.

Gap junctions in thyroid epithelium of the rat

Gap junctions were observed on the lateral plasma membrane of the typical thyroid epithelial cell in freeze-fracture preparations of rat thyroid gland. The gap junctions were 0.1 to 0.4 mum in diameter and were composed of closely packed, approximately 80 nm particles. They were located from 1 to 6 mum from the apical surface of the cell.

Changes in tight junctions of thyroid epithelium with changes in thyroid activity

The morphology of the tight junction of rat thyroid epithelium was examined in freeze-fractured material fixed in glutaraldehyde and briefly glycerinated. In normal thyroids the overall appearance of this junctional specialization resembled that of other cell types in many respects. Short-term changes in thyroid activity and hypophysectomy for 3 wk did not obviously affect the appearance of tight junctions. Feeding of the goitrogen, thiouracil, which stimulates secretion of thyroid-stimulating hormone, resulted in the appearance of some very narrow and some very wide, tight junctions or sometimes junctions with both wide and narrow regions within the same cell.

Evaluation of methods for reestablishment of L-cell suspension cultures directly from liquid nitrogen stored stocks

Methods were developed and evaluated for the preservation of tissue cells grown in suspension culture and the reestablishment of suspension cultures directly from inoculum stored at -175 C. The factors investigated were processing pH, temperature of processing, freezing medium, and method of inoculation of the starter suspension cultures from the frozen stock (-175 C). Three parameters, cell viability, cell size, and growth potential in suspension culture after freezing, were used to evaluate the various factors. The results indicate that cells processed at 4 C, frozen at 1 C per min to -50 C in a medium containing 5% dimethyl sulfoxide plus 10% bovine serum at concentrations of 2 x 10(7) to 4 x 10(7) cells/ml, and stored at -175 C will reestablish suspension cultures directly from frozen seed. A 1-ml amount of frozen stock inoculated into 99 ml of medium routinely produced 2 x 10(6) to 3 x 10(6) viable cells/ml (2 x 10(8) to 3 x 10(8) total cells) in suspension culture in 4 to 5 days. Inoculum preserved by this procedure grew equally well in either serum-free or serum-containing growth medium.

Evaluation of factors related to growth of Rift Valley fever virus in suspended cell cultures

The effect of several controlled variables on the peak titer and fold increase of Rift Valley fever virus grown in suspension culture on two variants of Earle's L cell, L-DR and L-MA clone 1-1, was studied. No significant amount of cell-associated virus was found at 24 hr, indicating a release of virus soon after its formation. Mild sonic treatment of the virus produced in serum-free medium increased the infective titer about 10x. This difference was not observed with virus produced in medium supplemented with serum. Peak titer was not affected by medium used during the infection period, by multiplicity of inoculum (MOI), or by initial cell concentration within the test range of 10(4) to 2 x 10(6) cell/ml. Cell strain employed influenced titer, because the L-DR cell did not produce virus efficiently at low MOI and low initial cell concentration. The time of peak titer and fold replication was dependent on MOI and initial cell concentration. Differences in virus propagation in monolayer and suspension systems are discussed.

Interacting factors that influence long-term storage of live Pasteurella tularensis vaccine and Rift Valley fever virus

Studies were conducted on the interaction of various parameters which affect the storage stability and growth potential of liquid cultures of Pasteurella tularensis live vaccine strain (LVS) and Rift Valley fever virus Van Wyk strain (RVFV). Storage variables studied with LVS included four storage temperatures (4, -20, -65, -175 C), single and multiple freeze-thaw cycles, two freezing and two thawing rates (slow and fast), various inoculum levels (1, 3, 5, and 10%) for the determination of growth potential, and the retention of immunizing potential (mice and guinea pig) after storage. Neither the freezing rate nor the number of freeze-thaw cycles seriously affected the growth of LVS after storage at -175C; however, the slow rate of thaw proved deleterious as were all temperatures of storage except -175 C after 1 year of storage, as shown by both criteria of evaluation. RVFV produced in two combinations of cell lines and media (LM cell line-199 peptone medium and LDR cell line-Eagle's minimum essential medium) was stored at three serum levels (10, 20, 40%), three pH values (6.2., 7.0, 7.8), and three temperatures (-20, -65, -175 C). These studies indicated: (i) virus produced in the LDR cell line and Eagle's medium was more stable than that produced in the LM cell line and 199 peptone medium for either short- or long-term storage; (ii) serum levels did not affect stability; and (iii) low pH resulted in losses during long-term storage under all conditions tested. Thus, cryogenic storage is advantageous for stock culture maintenance of bacteria and viruses and for other similar applications.