bluuebunny/crossref_metadata_2025 huggingface dataset:
Birth prevalence of congenital heart defects in Western Australia, 1990–2016
Authors: Hansen Michele , Greenop Kathryn , Yim Deane , Ramsay James , Thomas Yarlalu , Baynam Gareth S
Published: May 2021

Aim

To describe the birth prevalence and characteristics of congenital heart defects in a geographically defined Australian population.

Methods

This descriptive, population‐based study examined congenital heart defects in live births, stillbirths and pregnancy terminations ascertained by the Western Australian Register of Developmental Anomalies, 1990–2016. Birth prevalence (per 1000 births) was stratified by severity, known cause, maternal and birth characteristics, and primary diagnosis; and prevalence ratios were calculated for Aboriginal versus non‐Aboriginal births. Temporal trends in prevalence, diagnosis age and infant mortality were examined.

Results

For births 1990–2010 (allowing 6 years for complete case ascertainment by 2016), 6419 cases were identified; prevalence was 11.5 per 1000 births (95% confidence interval (CI), 11.2–11.8). Severe defects were ascertained in 2.5 per 1000 births (95% CI 2.4–2.7). Most cases were liveborn (5842, 91.0%), and 28.9% had other birth defects. Prevalence was slightly higher in Aboriginal births (prevalence ratio 1.1; 95% CI 1.0–1.2); and the infant mortality rate more than doubled (13.4% vs. 5.8%, P < 0.001). Prenatal diagnosis increased over time but, in remote areas, was significantly lower for Aboriginal versus non‐Aboriginal cases (3.1% vs. 9.3%; P = 0.008). A cause was identified in 920 cases (14.3%), more often for severe defects (347, 24.4%); 63% of known causes were rare diseases. Congenital heart defects associated with fetal alcohol spectrum disorder were much more common in Aboriginal births (prevalence ratio 82; 95% CI 28–239).

Conclusions

Earlier detection of congenital heart defects and improved survival has occurred over time, although discrepancies between ethnic groups and regions warrant further investigation and strategic action.
Development of a ball back extrusion technique for texture analysis of fluid food
Authors: Chen Wei , Hadde Enrico K. , Chen Jianshe
Published: May 2021

Textural properties of a food not only influence consumers' sensory preference of the product but also more importantly influence the strategy of food oral manipulation. Availability of reliable instrumental techniques has always been sought by food industry for proper assessment of food texture both in lab and online quality control. In this work a set of ball back extrusion (BBE) geometries with various ball/cup diameters (38/40, 35/40, 31.5/40, 24.5/28, all in mm) have been assessed as a fixture of a standard texture analyzer for flowability and consistency test of fluid foods. The feasibility of the new design has been tested against plate back extrusion (PBE), a current standard, for a set of fluid food materials (3 near Newtonians and 2 non‐Newtonians). Pressing force and apparent maximum stress were used to quantify the flowability of fluid materials. It was observed that both techniques were able to reflect the rheological nature of the samples and were able to distinguish flowability for both Newtonian and Non‐Newtonian fluids. However, the new design shows advantages against the plate back extrusion with much improved stability. Results show that BBE could replace the conventional plate‐back extrusion to evaluate the flow properties of fluid foods in an industrial environment. The geometries of 35/40 or 24.5/28 ball/cup diameters (aspect ratio 0.875) were shown to give most satisfactory performance. The device is specifically suitable for texture classification of fluid foods for dysphagia management.
The limits of demographic buffering in coping with environmental variation
Authors: Rodríguez‐Caro Roberto C. , Capdevila Pol , Graciá Eva , Barbosa Jomar M. , Giménez Andrés , Salguero‐Gómez Rob
Published: May 2021

Animal populations have developed multiple strategies to deal with environmental change. Among them, the demographic buffering strategy consists in constraining the temporal variation of the vital rate(s) that most affect(s) the overall performance of the population. Tortoises are known to buffer their temporal variation in adult survival, which typically has the highest contribution to the population growth rate λ, at the expense of a high variability on reproductive rates, which contribute far less to λ. To identify the effects of projected increases in droughts in its natural habitat, we use field data collected across 15 locations of Testudo graeca in southeast Spain over a decade. We analyse the effects of environmental variables on reproduction rates. In addition, we couple the demographic and environmental data to parameterise an integral projection model to simulate the effects of different scenarios of drought recurrence on λ under different degrees of intensity in the survival–reproduction tradeoff. We find that droughts negatively affect the probability of laying eggs; however, the overall effects on λ under the current drought recurrence (one/decade) are negligible when survival is constant (independent of the reduction of reproduction by drought events) and when survival increased as a tradeoff with the reduction of reproduction rates, with a threshold to population viability at three or more droughts/decade. Additionally, we show that, although some species may buffer current environmental regimes by carefully orchestrating how their vital rates vary through time, a demographic buffering strategy is insufficient to ensure population viability in extreme regimes. Our findings support the hypothesis that the demographic buffering strategy has a limit of effectiveness when adverse conditions occur frequently. Our methodological approach provides a framework for ecologists to determine how effective the management of environmental drivers can be for demographically buffering populations, and which scenarios may not provide long‐term population persistence.
Anxiety and depression in patients who receive anti‐VEGF treatment and the usability and feasibility of e‐mental health support: the E‐PsEYE pilot study
Authors: van der Aa Hilde PA , van Rens Ger HMB , Verbraak Frank D , Bosscha Machteld , Comijs Hannie C , van Nispen Ruth MA
Published: May 2021

Purpose

E‐PsEYE is an internet‐based, guided self‐help course, following the principles of cognitive behavioural therapy, to reduce anxiety and depression in patients with retinal exudative diseases who receive anti‐vascular endothelial growth factor (anti‐VEGF) treatment. The purpose of this study was to determine the prevalence and related factors of anxiety and depression in this population and evaluate the usability and feasibility of E‐PsEYE.

Methods

Symptoms of anxiety and depression and related factors were determined in 90 patients (mean age 77 years, 58% female), based on multiple logistic regression analysis. Five patients with mild to moderate depression/anxiety tested the usability of E‐PsEYE. They were asked to think aloud while completing two modules of the intervention and freely explore system features. The feasibility of the total E‐PsEYE intervention was tested in 14 patients with mild to moderate depression/anxiety, based on a single arm pre‐post study with a follow‐up of three months: fidelity, acceptability, feasibility of study methods and potential effectiveness were explored.

Results

Fifty‐three percent of the total study population experienced at least mild anxiety and/or depression symptoms. Especially female patients (odds ratio (OR) 3.89, 95% confidence interval (CI) 1.33–11.40), those who experienced limitations in daily life activities due to vision loss (OR 9.67; 95% CI 3.18–29.45) and those who experienced loneliness (OR 3.53, 95% CI 1.14–10.95) were more likely to have anxiety/depression. The usability study raised several possibilities for improvement, based on which E‐PsEYE was improved. The feasibility study showed adequate fidelity and acceptability. Most participants were satisfied with the results (79%). There was a high response rate, no loss to follow‐up and mental health problems decreased in more than half of the patients. The Wilcoxon signed rank test indicated lower post‐test ranks compared to pre‐test ranks (depression Z −1.34, p = 0.18; anxiety Z −1.45, p = 0.15).

Conclusions

Mental health problems are prevalent in patients who receive anti‐VEGF treatment. Healthcare providers should recognise these problems and related factors in order to refer patients to appropriate care in a timely manner. Outcomes on the usability and feasibility of E‐PsEYE are promising as a prelude to performing a randomised controlled trial, which will shed more light on its (cost‐)effectiveness.
Cotyledons facilitate the adaptation of early‐maturing soybean varieties to high‐latitude long‐day environments
Authors: Xu Xin , Zhang Lixin , Cao Xiaoning , Liu Lifeng , Jiang Bingjun , Zhang Chunlei , Jia Hongchang , Lyu Xiangguang , Su Yumei , Cai Yupeng , Liu Luping , Zhang Shengrui , Chen Fulu , Wu Cunxiang , Liu Bin , Hou Wensheng , Sun Shi , Lai Jinsheng , Han Tianfu
Published: May 2021

Soybean (Glycine max), a typical short‐day plant (SDP) domesticated in temperate regions, has expanded to high latitudes where daylengths are long from soybean emergence to bloom, but rapidly decrease from seed filling to maturity. Cotyledons are well known as the major storage organs in seeds, but it is unclear whether developing cotyledons store flowering substances at filling stage in SD for upcoming seedlings, or instead respond to photoperiod for floral induction after emergence of matured seeds in long‐day (LD). Here, we report that cotyledons accelerate flowering of early‐maturing varieties not resulting from stored floral stimuli but by perceiving photoperiod after emergence. We found that light signal is indispensable to activate cotyledons for floral induction, and flowering promoting gene GmFT2a is required for cotyledon‐dependent floral induction via upregulation of floral identity gene GmAP1. Interestingly, cotyledons are competent to support the entire life cycle of a cotyledon‐only plant to produce seeds, underlying a new photoperiod study system in soybean and other dicots. Taken together, these results demonstrate a substantial role for cotyledons in flowering process, whereby we propose a ‘cotyledon‐based self‐reliance’ model highlighting floral induction from emergence as a key ecological adaptation for rapid flowering of SDPs grown in LD environments at high latitudes.
Site Visit Frequency Policies for Mobile Family Planning Services
Authors: De Vries Harwin , Swinkels Lisa E. , Van Wassenhove Luk N.
Published: May 2021

Improving access to family planning services is key to achieving many of the United Nations sustainable development goals. To scale up access in remote areas and urban slums, many developing countries deploy mobile family planning teams that visit “outreach sites” several times per year. Visit frequencies have a significant effect on the total number of clients served and hence the impact of the outreach program. Using a large dataset of visits in Madagascar, Uganda, and Zimbabwe, our study models the relationship between the number of clients seen during a visit and the time since the last visit and uses this model to analyze the characteristics of optimal frequencies. We use the latter to develop simple frequency policies for practical use, prove bounds on the worst‐case optimality gap, and test the impact of the policies with a simulation model. Our main finding is that despite the complexity of the frequency optimization problem, simple policies yield near‐optimal results. This holds even when few data are available and when the relationship between client volume and the time since the last visit is misspecified or substantially biased. The simulation for Uganda shows a potential increase in client numbers of between 7% and 10%, which corresponds to more than 12,000 additional families to whom family planning services could be provided. Our results can assist policymakers in determining when to start data‐driven frequency determination and which policies to implement.
Incentivizing Farmers to Invest in Quality through Quality‐Based Payment
Authors: Ayvaz‐Çavdaroğlu Nur , Kazaz Burak , Webster Scott
Published: May 2021

We consider a for‐profit cooperative that sets a quality‐based payment to its risk‐averse farmers in order to incentivize them to invest in quality improvements. The quality of the farmer's harvest is affected by his investments during the growing season. To satisfy both the farmer and the cooperative, the payment must be competitive with the open‐market prices. Cooperatives often set payments that mimic the open‐market prices; however, this practice fails to incentivize farmers to invest in quality. Our work is motivated by the evidence of farmer underinvestment in crop quality in the olive oil industry. We define and analyze a model of this system where farmers operate under random yield, quality, and open‐market price. We find that farmers consistently underinvest in crop quality under the payment policy that mimics the open‐market prices because (1) the cooperative can command a higher retail price than a farmer and (2) farmers are risk averse. We propose two alternative payment policies that are new to the agricultural literature, both of which can coordinate farmer decisions with the system but differ in terms of ease of implementation and susceptibility to risk aversion. We identify an easy‐to‐implement policy that can lead to meaningful gains when introduced in conjunction with crop insurance. We calibrate our model using data from the olive oil industry in Turkey and find a profit improvement of 10–15% over the current open‐market payment approach.
Designing a Sustainable Two‐Tier Service System with Customer's Asymmetric Preference for Servers
Authors: Zhang Zhe George , Yin Xiaoling
Published: May 2021

This study considers a public service system consisting of two service providers with different service capacities and qualities, such as healthcare or transportation systems. Such a system is called a two‐tier service system (TTS). The service provider with higher service capacity and quality charges a higher price and is called a “charge service provider,” denoted by CSP, while the other service provider charges a lower price and is called a “free service provider,” denoted by FSP. We study the TTS where customers prefer the CSP to the FSP in spite of the higher price of CSP. The strong preference of CSP to FSP, which can be due to bounded rationality, leads to imbalanced workload for the TTS which implies an inefficient use of limited resources. Although both can offer a common set of services, the CSP is overly demanded and highly congested, while the FSP is under‐utilized. We first study analytically an extreme case where the preference for CSP is so strong that customers choosing the CSP are delay insensitive and those choosing the FSP are delay sensitive. Then, we extend our analysis to more general cases where customers are delay sensitive in both channels and have asymmetric preferences for service providers. Using a stylized queueing model and equilibrium customer choice analysis, we show that under certain conditions, the two‐tier system may reduce congestion and the total social cost in the system. This study offers social planners the guidance in designing less congested, more cost‐efficient, and sustainable public service systems.
Aggregation Bias in Estimating Log‐Log Demand Function
Authors: Wang Zizhuo , Yang Chaolin , Yuan Hongsong , Zhang Yaowu
Published: May 2021

In this study, we consider the problem of estimating demand functions using historical sales data. In particular, we study how using aggregate data may result in bias in such estimations. We consider a log‐log demand model, and two ways of how the price in the aggregate data is calculated, simple average price or weighted average price. We study whether there exists estimation bias in each of the two cases as well as the direction of the bias. We show that in general, the correlation between “average price” and “price dispersion” in each time period has an effect on the direction of the bias. We then propose ways to reduce the aggregation bias. We prove that when the price processes satisfy certain mild conditions, our debiasing procedure can recover the true parameters asymptotically. We also obtain statistical properties of the debiased parameters. We perform numerical experiments on both synthetic and real data to demonstrate the effectiveness of our approach. The numerical results show that our proposed bias mitigation approach has the potential of effectively reducing the bias in both synthetic and practical settings.
Water transport in fleshy fruits: Research advances, methodologies, and future directions
Authors: Hou Xuemin , Li Hao , Zhang Wendong , Yao Zhenzhu , Wang Yaosheng , Du Taisheng
Published: May 2021

Fruits are reproductive organs in flowering plants and the harvested products of many agricultural crops. They play an increasingly important role in the human diet due to their nutritional values. Water is the most abundant component of most fleshy fruits, and it is essential for fruit growth and quality formation. Water is transported to the fruit via the vascular system (xylem and phloem) and lost to the air through the fruit surface due to transpiration. This minireview presents a framework for understanding water transport in fleshy fruits along with brief introductions of key methodologies used in this research field. We summarize the advances in the research on the patterns of water flow into and out of the fruit over development and under different environmental conditions and cultural practices. We review the key findings on fruit transpiration, xylem transport, phloem transport, and the coordination of water flows in maintaining fruit water balance. We also summarize research on post‐vascular water transport mediated by aquaporins in fruits. More efforts are needed to elucidate the mechanisms by which different environmental conditions impact fruit water transport at the micro‐level and to better understand the physiological implications of the coordination of water flows. Incorporating fruit water transport into the research area of plant hydraulics will provide new insights into water transport in the soil‐plant‐atmosphere continuum.
Effects of fire seasonality and intensity on resprouting woody plants in prairie‐forest communities
Authors: Meunier Jed , Holoubek Nathan S. , Johnson Yari , Kuhman Tim , Strobel Brad
Published: May 2021

Woody plant expansion is one of the greatest contemporary threats to fire‐dependent ecosystems. Reducing woody plant prevalence is often a primary objective of prescribed burns, yet little attention has been given to understanding the efficacy of burning to reduce their abundance. Fire intensity characteristics and plant phenology/physiology, which are sometimes presented as competing hypotheses, influence how woody plants respond to a fire event. Little work has been done in the prairie‐forest region of the upper Midwest to understand how fire characteristics interact with woody species phenology and/or physiology. Using a controlled field experiment, we examined effects of timing (seasonality) and intensity (temperature and duration) of fires on top‐kill and resprouting of three invasive woody plants in this region (common buckthorn,Rhamnus cathartica; bush honeysuckles,Loniceraspp.; and a native species, northern pin oakQuercus ellipsoidalis). Honeysuckles and pin oak burned in the spring dormant period, a common practice in the region, resulted in low levels of top‐kill and high levels of resprouting. Burning during the late growing season yielded highest levels of top‐kill and lowest levels of resprouting for honeysuckles and pin oaks. However, there was no apparent effect of season or fire intensity treatment for buckthorn stems. Under all treatment combinations, buckthorn was easily top‐killed but resprouted prolifically. Collectively, most prescribed burning in the Midwest appears to be conducted during the least effective season (early growing season), when top‐kill is reduced and/or resprouting most pronounced. Our results indicate that fire use could be better prescribed in this region for controlling woody plants.
Eucalypt plantations for forest restoration in a fire‐prone mosaic of grasslands and forests in northern Argentina
Authors: Montiel Rosario , Zaninovich Silvia C. , Bedrij Natalia A. , Insaurralde Ariel , Verdoljak Juan J. , Fontana José L. , Gatti Ma. Genoveva
Published: May 2021

In ecosystems with grassland‐forest boundaries, tree plantations could be used to promote forest restoration. In the Humid Chaco region of central South America, fire is one of the main disturbances that shapes the landscape. As eucalypt plantations are flammable, the contribution they can make to forest restoration is questionable. We planted saplings of five native tree species in three different environments (forests, grasslands, and eucalypt plantations) and assessed microclimatic conditions likely to influence sapling survival and growth. After 1 year, accidental fires that affected much of the study area allowed us to investigate the susceptibility of different environments to fire occurrence and post‐fire sapling survival. We planted 600 saplings in four plots per environment. We evaluated fire occurrence in the study area for 2 years and ask whether this factor affects sapling survival. In grasslands, microclimatic conditions were more extreme than in plantations. Plantations and forests showed high pre‐fire sapling survival but growth was almost double in plantations, similar to grasslands for most species. In the study area, fire frequency was similar in plantations and grasslands, whereas forests plots never burnt during the 2‐year study period. Fire reduced sapling survival in plantations, but not in grasslands where survival was low and similar in burned and unburned plots. For top‐killed plants, post‐fire resprouting ability was species‐specific. While more firm conclusions await future studies with even larger sample sizes, our results indicate that fire management may be necessary in order to use eucalypt plantations as nurses in this fire‐prone ecosystem.
Information anchored reference‐based sensitivity analysis for truncated normal data with application to survival analysis
Authors: Atkinson Andrew , Cro Suzie , Carpenter James R. , Kenward Michael G.
Published: May 2021

The primary analysis of time‐to‐event data typically makes the censoring at random assumption, that is, that—conditional on covariates in the model—the distribution of event times is the same, whether they are observed or unobserved. In such cases, we need to explore the robustness of inference to more pragmatic assumptions about patients post‐censoring insensitivity analyses. Reference‐based multiple imputation, which avoids analysts explicitly specifying the parameters of the unobserved data distribution, has proved attractive to researchers. Building on results for longitudinal continuous data, we show that inference using a Tobit regression imputation model for reference‐based sensitivity analysis with right censored log normal data isinformation anchored, meaning the proportion of information lost due to missing data under the primary analysis is held constant across the sensitivity analyses. We illustrate our theoretical results using simulation and a clinical trial case study.
The Association Between Alterations in Redox Homeostasis, Cortisol, and Commonly Used Objective and Subjective Markers of Fatigue in American Collegiate Football
Authors: McKay Benjamin A. , Delaney Jace A. , Simpkin Andrew , Larkin Theresa , Murray Andrew , Pedlar Charles R. , Lewis Nathan A. , Sampson John A.
Published: May 2021

Purpose: To assess associations between a free oxygen radical test (FORT), free oxygen radical defense test (FORD), oxidative stress index, urinary cortisol, countermovement jump (CMJ), and subjective wellness in American college football. Methods: Twenty-three male student athlete American college football players were assessed over 10 weeks: off-season conditioning (3 wk), preseason camp (4 wk), and in season (3 wk). Assessments included a once-weekly FORT and FORD blood sample, urinary cortisol sample, CMJ assessment including flight time, reactive strength index modified and concentric impulse, and a daily subjective wellness questionnaire. Linear mixed models analyzed the effect of a 2 within-subject SD change in the predictor variable on the dependent variable. The effects were interpreted using magnitude-based inference and are presented as standardized effect size (ES) ± 90% confidence intervals. Results: Small negative associations were observed between FORT–flight time, FORT–fatigue, FORT–soreness (ES range = −0.30 to −0.48), FORD–sleep (ES = 0.42 ± 0.29), and oxidative stress index soreness (ES = 0.56 ± 0.29). Small positive associations were observed between FORT–cortisol (ES = 0.36 ± 0.35), FORD–flight time, FORD reactive strength index modified and FORD–soreness (0.37–0.41), oxidative stress index concentric impulse (ES = 0.37 ± 0.28), and with soreness–concentric impulse, soreness–flight time, and soreness reactive strength index modified (0.33–0.59). Moderate positive associations were observed between cortisol–concentric impulse and cortisol–sleep (0.57–0.60). Conclusion: FORT/FORD was associated with CMJ variables and subjective wellness. Greater amounts of subjective soreness were associated with decreased CMJ performance, increased FORT and cortisol, and decreased FORD.
Hip and Trunk Muscle Activity and Mechanics During Walking With and Without Unilateral Weight
Authors: Graber Kerri A. , Loverro Kari L. , Baldwin Mark , Nelson-Wong Erika , Tanor Joshua , Lewis Cara L.
Published: May 2021

Pelvic drop is caused by decreased hip abductor muscle activity and is associated with lower-extremity injury. Hip abductor strengthening exercises are well established; however, no standard method exists to increase hip abductor activity during functional activities. The purpose of this research was to study the effects of walking with a unilateral weight. A total of 26 healthy adults walked on an instrumented treadmill with and without handheld weight (15%–20% body weight). Muscle activity, kinematic, and kinetic data were collected using surface electromyography, motion capture, and force plates, respectively. Average hip and trunk muscle activity, hip, pelvic, and trunk angles, and peak internal hip moments during stance were compared for each side (contralateral/ipsilateral to the weight) between conditions (unweighted/weighted) using a generalized linear model with generalized estimating equation correction. Interactions between condition and side were observed for muscle activity, frontal plane pelvic and trunk angles, and frontal plane hip moments (P ≤ .003). Compared with the unweighted condition, the weighted condition had higher hip abductor activity contralateral to the weight (P < .001), while no change was found ipsilateral to the weight (P ≥ .790). Similar changes were found for kinematic and kinetic variables. Walking with a unilateral weight may be a therapeutic option to increase functional hip abductor activity.
Increases in Load Carriage Magnitude and Forced Marching Change Lower-Extremity Coordination in Physically Active, Recruit-Aged Women
Authors: Dever Dennis E. , Krajewski Kellen T. , Johnson Camille C. , Allison Katelyn F. , Ahamed Nizam U. , Lovalekar Mita , Mi Qi , Flanagan Shawn D. , Anderst William J. , Connaboy Chris
Published: May 2021

The objective was to examine the interactive effects of load magnitude and locomotion pattern on lower-extremity joint angles and intralimb coordination in recruit-aged women. Twelve women walked, ran, and forced marched at body weight and with loads of +25%, and +45% of body weight on an instrumented treadmill with infrared cameras. Joint angles were assessed in the sagittal plane. Intralimb coordination of the thigh–shank and shank–foot couple was assessed with continuous relative phase. Mean absolute relative phase (entire stride) and deviation phase (stance phase) were calculated from continuous relative phase. At heel strike, forced marching exhibited greater (P < .001) hip flexion, knee extension, and ankle plantar flexion compared with running. At mid-stance, knee flexion (P = .007) and ankle dorsiflexion (P = .04) increased with increased load magnitude for all locomotion patterns. Forced marching (P = .009) demonstrated a “stiff-legged” locomotion pattern compared with running, evidenced by the more in-phase mean absolute relative phase values. Running (P = .03) and walking (P = .003) had greater deviation phase than forced marching. Deviation phase increased for running (P = .03) and walking (P < .001) with increased load magnitude but not for forced marching. With loads of >25% of body weight, forced marching may increase risk of injury due to inhibited energy attenuation up the kinetic chain and lack of variability to disperse force across different supportive structures.
Advances in the Microbiology of Stenotrophomonas maltophilia
Authors: Brooke Joanna S.
Published: May 2021

Stenotrophomonas maltophilia
is an opportunistic pathogen of significant concern to susceptible patient populations. This pathogen can cause nosocomial and community-acquired respiratory and bloodstream infections and various other infections in humans.
Stability of fluorescent antibody conjugates stored under various conditions
Authors: Green J H , Gray S B , Harrell W K
Published: May 2021

Two experiments were carried out to determine the stability of fluorescent antibody conjugates. In experiment 1, Francisella tularemia conjugates in the lyophilized state retained their original staining titer for 1,294 days when stored at 25, 4 to 5, and -20 C; at 37 C the conjugates were stable for at least 65 days. In the liquid state at pH 7.4 and 8.0 these conjugates were stable for 1,294 days at 4 to 5 and -20 C, whereas those stored at 25 C remained stable through days 473 and 160 of storage, respectively, after which the staining titer gradually dropped. In experiment 2 five previously lyophilized conjugates were rehydrated with three different diluents and stored at 4 to 5 C for up to 600 days at their working dilutions. All of these conjugates retained their original staining titer during the test period except an anti-human globulin conjugate rehydrated with phosphate-buffered saline. Recommendations are made for the long-term storage of fluorescent antibody conjugates.
Electron capture gas chromatographic detection of acethylmethylcarbinol produced by neisseria gonorrhoeae
Authors: Morse C D , Brooks J B , Kellogg D S
Published: May 2021

Acetylmethylcarbinol (acetoin) production by Neisseria gonorrhoeae and other Neisseria species was established by gas-liquid chromatography and by mass spectrometric data. Sixty-nine isolates of Neisseria were tested by incubating them in a chemically defined fluid medium. The medium was extracted with organic solvents and derivatized with heptafluorobutryic anhydride for gas chromatography and mass spectrometry. Cultures of 58 of the same strains were tested with the conventional Voges-Proskauer reagents, and results were compared with those of gas-liquid chromatography. When glucose was used as an energy source, N. gonorrhoeae, some N. meningitidis, and N. lactamica produced enough acetoin in 16 h to be detectable by either method, whereas other Neisseria species produce amounts detectable only by gas chromatography. The conventional acetylmethylcarbinol test with the chemically defined medium and maltose as an energy source might be used to develop methods that would differentiate certain members of the genus, including the pathogenic species.
Recovery of pathogenic fungi from clinical specimens submitted for mycobacteriological culture
Authors: Roberts G D , Karlson A G , DeYoung D R
Published: May 2021

A total of 332 major pathogenic fungi were isolated from specimens cultured onto both fungal culture media and media used for culturing mycobacteria from January 1968 to June 1975. Only 72 (21.7%) fungi were recovered on media used for culturing mycobacteria. The effect of sodium hydroxide treatment was evaluated and shown to be detrimental to the recovery of fungi. It is recommended that clinical laboratories not rely on mycobacteriological cultures to recover fungal pathogens.
Evaluation of a rubella hemagglutination inhibition test system
Authors: Smith J A , Cummins A C
Published: May 2021

Two systems for measurement of rubella hemagglutination inhibition antibodies were compared. One had chick erythrocytes as indicator and the other, which is available in kit form ("Rubindex," Ortho-Diagnostics), uses human group O erythrocytes. Correlation to within one dilution of each other was noted in 92% of the tests. The Rubindex system has the advantage of longer shelf life of reagents and also does not require one of the absorption steps necessary for the other method, thus saving technologist's time.
Comparison of the complement fixation test and counterelectrophoresis test for the detection of antibodies in Chagas disease
Authors: Knight R A , Rocha H , Kaye D
Published: May 2021

Sera from 452 patients and blood donors were tested for antibodies to Tryp-anosoma cruzi. The complement fixation test and a counterelectrophoresis test were used. The results showed that both tests agreed in 92% of the sera. However, the counterelectrophoresis test was not as sensitive as the complement fixation test.
Comparison of Amino Acid Decarboxylase and Dihydrolase Results by Moeller, Rapid, and Replicator Plate Methods
Authors: Jones Ronald N. , Fuchs Peter C. , Sniderman Steve
Published: May 2021

A slightly modified Moeller medium for amino acid decarboxylase and dihydrolase testing by the replicator method correlated 96 to 99% with the reference Moeller broth method. False positive results were not encountered in this study.
Isolation and characterization of a catalase-negative strain of Staphylococcus aureus
Authors: Tu K K , Palutke W A
Published: May 2021

An unusual, naturally occurring strain of Staphylococcus aureus is characterized. It is typical in colony and cellular morphology, coagulase production, and other biochemical reactions as compared to S. aureus (ATCC-25923), except that it is catalase negative and fails to ferment mannitol anaerobically.
Computer-assisted bacterial identification utilizing antimicrobial susceptibility profiles generated by autobac 1
Authors: Sielaff B H , Johnson E A , Matsen J M
Published: May 2021

A computer program was developed to identify bacteria solely on the basis of their relative susceptibility to various antimicrobial agents. A sample of 481 clinical isolates from nine of the most commonly isolated gram-negative groups was identified by the quadratic discriminant function technique. Various combinations of antimicrobials were tried, and one set of 18 resulted in a more than 97% correlation with conventional identification procedures. The antimicrobial set could be decreased to 14, while a better than 95% correlation with the conventional procedures was maintained.
Cholesterol requirement of mycoplasmas as determined by microtiter test using polyene antibiotics
Authors: Grabowski M W , Rottem S , Barile M F
Published: May 2021

A microtiter metabolic inhibition test was used to determine the effect of filipin and lucensomycin on the growth of representative species of Mycoplasma and Acholeplasma. The cholesterol-requiring species tested were found to be very susceptible to the two antibiotics, whereas the cholesterol nonrequiring species were not.The utilization of this method for differentiation between the Mycoplasma and Acholeplasma species is suggested and its advantages are discussed.
Comparative evaluation of the Candida agglutinin test, precipitin test, and germ tube dispersion test in the diagnosis of candidiasis
Authors: Oblack D , Schwarz J , Holder I A
Published: May 2021

Normal sera and sera from burned patients were examined for Candida agglutinin titers, precipitin titers, and the ability to disperse germ tubes of Candida albicans in an attempt to determine whether germ tube dispersion is correlated with Candida infection as animal models have indicated. Other investigators have reported that immunoglobulin G antibody to Candida interferes with a serum clumping factor resulting in germ tube dispersion. Germ tube dispersion in sera from burned patients with varying degrees of Candida infection is significantly greater than that found in uninfected controls. In addition, the germ tube dispersion test indicated the presence of Candida infection in several patients who had clinical evidence of infection but no detectable agglutinins or precipitins.
Rapid in vitro conversion and identification of Coccidioides immitis
Authors: Sun S H , Huppert M , Vukovich K R
Published: May 2021

Since many contaminating nonpathogenic fungi resemble Coccidioides immitis culturally, isolates from patients must be inoculated into laboratory animals to confirem identification as C. immitis. This procedure is time-consuming, expensive, and not generally available in clinical laboratories. When cultures of C. immitis were grown in slide cultures on modified Converse liquid medium in purified agar and incubated at 40 C in a candle jar, all 57 isolates demonstrated inhibition of mycelial growth and conversion of arthrospores to endosporulating spherules in 3 to 5 days. Representative isolates of six species of nonpathogenic fungi that resembled C. immitis culturally either did not grow or failed to produce endosporulating spherules under the same conditions. This procedure is recommended for confirming the identication of a culture as C. immitis.
Specific immunological test for the rapid identification of members of the genus Histoplasma
Authors: Standard P G , Kaufman L
Published: May 2021

A sensitive and specific immunological method was developed for rapid identification of the mycelial forms of Histoplasma capsulatum var. capsulatum, H. capsulatum var. duboisii, and H. farciminosum and for separation of these pathogenic fungi from morphologically similar hyphomycetes and other fungal pathogens. This method is based on the fact that all of the Histoplasma spp. produce H and M histoplasmin antigens, whereas the other fungi do not. Inocula consisting of heavy mycelial growth from a pure, full-grown culture were transferred into flasks containing small volumes of brain heart infusion broth. These cultures were placed on a shaker and grown at 25 C. Using the micro-immunodiffusion technique and antisera containing antibodies to H and M precipitinogens, we detected exoantigens in 3-day-old brain heart infusion culture supernatants concentrated 25 and 50 times. The ability of the procedure to identify Histoplasma spp. was evaluated by testing 96 unknown mycelial cultures that grossly or microscopically resembled Histoplasma spp. Three- and six-day-old concentrated culture supernatants prepared from each unknown were tested against rabbit anti-Arthroderma tuberculatum, Chrysosporium keratinophilum, H. capsulatum var. duboisii, and Corynascus (Thielavia) sepedonium sera and human histoplasmosis case serum. Each unknown was also identified by conventional laboratory procedures involving cultural and, where necessary, in vivo studies. In the comparative evaluation the immunological test was observed to be 100% sensitive. It permitted the accurate generic identification of the Histoplasma spp. within 5 days, in contrast to the average of 33 days required by the routine mycological procedure.
A new medium for the detection of gelatin-hydrolyzing activity of human dental plaque flora
Authors: Syed S A
Published: May 2021

A new medium for the detection of gelatin-hydrolyzing activity of human dental plaque flora by a simplified plate method is described. It is designed to support the growth of obligate anaerobes, facultative anaerobes, and aerobes. This medium can be used for the identification of gelatinase-producing organisms of clinical importance.
Identification of
Brucella abortus
Antibodies in Cattle Serum by Single Radial Diffusion
Authors: Iannelli Domenico , Diaz Ramon , Bettini T. Manlio
Published: May 2021

Single radial diffusion combined with the Rose Bengal test permitted rapid identification of all of the
Brucella abortus
-infected cattle in a study group of 689 animals.
Inactivation of viruses in serum with binary ethyleneimine
Authors: Bahnemann H G
Published: May 2021

The inactivation os six strains from three different groups of viruses with 0.001 M binary ethyleneimine at 37 C proceeded at the same rate in either bovine serum or cell culture medium. The inactivant did not impair the growth-promoting capacity of bovine serum used in cell culture, nor did it affect the antibody activity of guinea pig hyperimmune serum.
Gas chromatographic characterization of mycobacteria: analysis of fatty acids and trifluoroacetylated whole-cell methanolysates
Authors: Larsson L , Mårdh P A
Published: May 2021

Mycobacterium avium, M. bovis strain Bacillus Calmette-Guerin (BCG), M. kansasii, and M. tuberculosis were studied by gas-liquid chromatography. Methylated fatty acids of the mycobacterial lipids and trifluoroacetyl (TFA) derivatives of whole-cell methanolysates were analyzed. Both the fatty acid and the TFA chromatograms showed reproducible differences between the various mycobacteria studied. Chromatograms from different strains of one and the same species showed negligible differences. Fatty acid methyl esters and TFA methyl glycosides are probably the main constituents of the TFA chromatograms. TFA derivatives are easily prepared and the method provides a potential tool for species indentification of mycobacteria.
Evaluation of the hemolysis-in-gel test for the screening of rubella immunity and the demonstration of recent infection
Authors: Grillner L , Strannegård O
Published: May 2021

The hemolysis-in-gel method for detection of antibodies to rubella virus gave results which correlated well with results of hemagglutination inhibition and neutralization tests. With a diffusion time of 24 or 48 h, a linear correlation was obtained between the logarithm of antibody concentration and the diameter of the hemolytic zone. Fourfold, and even twofold, differences in serum antibody concentrations were shown to give statistically significant differences in hemolytic zone diameters. It could therefore be concluded that the hemolysis-in-gel test is well suited for the serological diagnosis of primary rubella infection, as well as of reinfection. The sensitivity of the hemolysis-in-gel test was comparable to that of the hemagglutination inhibition test. Pigeon erythrocytes were superior to sheep erythrocytes for use in the test. Studies of the antibody response after natural rubella infection or vaccination showed that the appearance and persistence of antibodies measured by hemolysis in gel is similar to that of hemagglutination inhibition antibodies.
Possibility of diagnosing meningitis by gas chromatography: cryptococcal meningitis
Authors: Schlossberg D , Brooks J B , Shulman J
Published: May 2021

Cerebrospinal fluid (CSF) from eight patients with cryptococcal meningitis, from ten patients with viral meningitis, and from four control patients without meningitis were analyzed by electron-capture gas-liquid chromatography (EC-GLC). All cryptococcal specimens had similar EC-GLC profiles, and these differed from those of the controls. Viral EC-GLC patterns were different from those obtained with specimens from the patients with cryptococcal infection and from the controls. In addition, specimens from patients with various types of viral infections gave profiles that differed from each other. Two normal CSFs were inoculated with Cryptococcus neoformans; aliquots of these cultures showed an EC-GLC pattern very similar to that seen in CSF of patients with cryptococcal meningitis. The EC-GLC procedure is rapid, reproducible, and easy to perform and may hold promise as an additional aid in the diagnosis of cryptococcal infection.
Blood culture technique based on centrifugation: developmental phase
Authors: Dorn G L , Haynes J R , Burson G G
Published: May 2021

A quantitative and flexible blood culture system based on centrifugation of lysed blood over a density layer is described. The effect of relative centrifugal force, centrifugation time, and two different density solutions on the recovery of Staphylococcus aureus, Escherichia coli, pseudomonas aeruginosa, and Candida albicans was determined. To demonstrate the versatility of this technique, the reisolation of 23 representative microorganisms from inoculated normal human blood was determined at a fixed centrifugation speed and time. The potential merits of this technique are discussed and compared with those of conventional blood culture methods.
Epidemiology of Pseudomonas aeruginosa infections: determination by pyocin typing
Authors: Bruun F N , McGarrity G J , Blakemore W S , Coriell L L
Published: May 2021

The epidemiology of hospital infections due to Pseudomonas aeruginosa was investigated by pyocin typing. The typing method, which determined the pyocin activity of clinical isolates of P. aeruginosa on 27 indicator strains, was 43.7% reproducible, but elimination of 9 indicator strains doubled the reproducibility and yielded more readable pyocin inhibition zones. Seventy-eight of 1,084 isolates (7.2%) were untypable. In the second part of the study, P. aeruginosa was isolated from 110 patients (5.4% of all admissions) in a 3-month period and typed with the revised method. Twenty pyocin types were identified, 10 of which were obtained from five or more patients. P. aeruginosa was isolated from 45 of 353 environmental samples, including water fountains, ice machines, bar soaps, and germicide solutions for toilet brushes. Twenty percent of the environmental samples were untypable but, among typable strains, the five most common environmental strains were the same as the strains most frequently isolated from patients. The organism was frequently isolated from noses (39%), throats (39%), and stools (29%) of patients with P. aeruginosa infections or colonizations in urine, sputum, surgical wounds, or skin lesions. Six of eight patients had P. aeruginosa in their tracheostomy wounds. Autoinfections by strains already acquired on carrier sites may be significant.
Use of biological characteristics to type Herpesvirus hominis types 1 and 2 in diagnostic laboratories
Authors: Marks-Hellman S , Ho M
Published: May 2021

Fifty clinical isolates of Herpesvirus hominis were typed by pock size on chicken embryo chorioallantoic membranes, sensitivity to heparin, and plaque formation on chicken embryo cell cultures. Of 19 isolates that were typed serologically, there was 100% concordance with respect to plaque formation. Pock size was incorrect in one instance and indeterminate in another. Heparin sensitivity was incorrect for one. Of 31 strains that were only biologically characterized, there were four for which heparin sensitivity did not agree with the other two characteristics. Of the three biological tests, the ability to form plaques in chick cell monolayer was the most reliable indicator type.