bluuebunny/crossref_metadata_2025 huggingface dataset:
Inverse wave scattering in the Laplace domain: A factorization method approach
Authors: Mantile Andrea , Posilicano Andrea
Published: February 2020

Let

Δ

Λ

≤

λ

Λ

\Delta _{\Lambda }\le \lambda _{\Lambda }

be a semi-bounded self-adjoint realization of the Laplace operator with boundary conditions (Dirichlet, Neumann, semi-transparent) assigned on the Lipschitz boundary of a bounded obstacle

Ω
\Omega

. Let

u

f

Λ

u^{\Lambda }_{f}

and

u

f

0

u^{0}_{f}

denote the solutions of the wave equations corresponding to

Δ

Λ

\Delta _{\Lambda }

and to the free Laplacian

Δ
\Delta

, respectively, with a source term

f
f

concentrated at time

t
=
0

t=0

(a pulse). We show that for any fixed

λ
>

λ

Λ

≥
0

\lambda >\lambda _{\Lambda }\ge 0

and any fixed

B
⋐

R

n

∖

Ω
¯

B\Subset {\mathbb R}^{n}\backslash \overline \Omega

, the obstacle

Ω
\Omega

can be reconstructed by the data
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartLayout 1st Row upper F Subscript lamda Superscript normal upper Lamda Baseline f left-parenthesis x right-parenthesis colon-equal integral Subscript 0 Superscript normal infinity Baseline e Superscript minus StartRoot lamda EndRoot t Baseline left-parenthesis u Subscript f Superscript normal upper Lamda Baseline left-parenthesis t comma x right-parenthesis minus u Subscript f Superscript 0 Baseline left-parenthesis t comma x right-parenthesis right-parenthesis d t comma 2nd Row x element-of upper B comma f element-of upper L squared left-parenthesis double-struck upper R Superscript n Baseline right-parenthesis comma normal s normal u normal p normal p left-parenthesis f right-parenthesis subset-of upper B period EndLayout">

F

λ

Λ

f
(
x
)

≔

∫

0

∞

e

−

λ

t

(

u

f

Λ

(
t
,
x
)
−

u

f

0

(
t
,
x
)

)

d
t
,

x
∈
B

,
 
f
∈

L

2

(

R

n

)

,
 

s
u
p
p

(
f
)
⊂
B

.

\begin{gather*} F^{\Lambda }_{\lambda }f(x)\coloneq \int _{0}^{\infty }e^{-\sqrt \lambda \,t}\big (u^{\Lambda }_{f}(t,x)-u^{0}_{f}(t,x)\big )\,dt,\\ x\in B\,,\ f\in L^{2}({\mathbb R}^{n})\,,\ \mathrm {supp}(f)\subset B\,. \end{gather*}

A similar result holds in the case of screens reconstruction, when the boundary conditions are assigned only on a part of the boundary. Our method exploits the factorized form of the resolvent difference
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="left-parenthesis minus normal upper Delta Subscript normal upper Lamda Baseline plus lamda right-parenthesis Superscript negative 1 Baseline minus left-parenthesis negative normal upper Delta plus lamda right-parenthesis Superscript negative 1">

(
−

Δ

Λ

+
λ

)

−
1

−
(
−
Δ
+
λ

)

−
1

(-\Delta _{\Lambda }+\lambda )^{-1}-(-\Delta +\lambda )^{-1}

.
The 𝐴𝐵𝐶-Conjecture implies uniform bounds on dynamical Zsigmondy sets
Authors: Looper Nicole
Published: February 2020

We prove that the

a
b
c

abc

-Conjecture implies upper bounds on Zsigmondy sets that are uniform over families of unicritical polynomials over number fields. As an application, we use the

a
b
c

abc

-Conjecture to prove that there exist uniform bounds on the index of the associated arboreal Galois representations.
Prognostic Impact of Histopathologic Features in Pulmonary Invasive Mucinous Adenocarcinomas
Authors: Chang Wei-Chin , Zhang Yu Zhi , Lim Eric , Nicholson Andrew G
Published: February 2020

Objectives

The prognostic significance of pathologic features and invasive size has not been well studied for invasive mucinous adenocarcinoma (IMA). This study evaluates the significance of pathologic features and invasive size in relation to clinical outcome.

Methods

We reviewed the pathologic features in 84 IMAs, including histologic pattern, nuclear atypia, mitosis, necrosis, and lymphovascular invasion. The invasive size was calculated from the total size using the percentage of invasive components. Cases were subdivided into two pathologic grades based on five pathologic features, and the pathologic grade and adjusted T (aT) stage were correlated with disease-free and overall survival (OS).

Results

Necrosis and N stage were significantly associated with aT stage, and a significant association was noted between OS and aT stage. Nuclear atypia, mitosis, and lymphovascular and pleural invasion also showed a significant association with OS. High-grade tumors showing a significantly worse OS compared with low-grade tumors, as well as pathologic grade (hazard ratio [HR], 2.337; P = .043) and aT stage (HR, 1.875; P = .003), were independent prognostic factors in multivariate analysis.

Conclusions

The pathologic grading system stratified IMAs into high- and low-grade tumors with significant differences in OS. Invasive size may provide a better prognostic stratification for OS.
Clinicopathologic Analysis of Oral and Maxillofacial Solitary Fibrous Tumor
Authors: de Morais Everton Freitas , Martins Hélder Domiciano Dantas , Rodrigues Katianne Soares , de França Glória Maria , da Silveira Éricka Janine Dantas , Freitas Roseana de Almeida
Published: February 2020

Objectives

The aim of this systematic review was to provide an overview of the oral and maxillofacial solitary fibrous tumor (SFT) in order to determine its clinicopathologic characteristics and biological behavior.

Methods

We conducted a systematic review in May 2019 in multiple databases. Cases diagnosed as SFT in the oral cavity and maxillofacial complex were included.

Results

Seventy-three published articles were included in our systematic review, corresponding to a total of 154 cases. SFT showed a slight female predilection (53.2%), and the cheek mucosa/cheek, tongue, and palate were the most affected anatomical sites. The mean size of SFT in the oral cavity and maxillofacial region at diagnosis was 1.4 cm. Histologic features of malignancy by morphologic analysis (P < .001) were significantly associated with a larger tumor size. Surgical excision was the most frequent therapeutic modality. Recurrence and metastasis were uncommon findings in our sample.

Conclusions

Histologic features of malignancy can be important parameters of tumor behavior. Adequate surgical treatment and long-term follow-up are required for these cases.
The Impact of the Foreign Corrupt Practices Act on Competitiveness, Bribery, and Investment
Authors: Arbatskaya Maria , Mialon Hugo M
Published: February 2020

The Foreign Corrupt Practices Act (FCPA) prohibits U.S.-related firms from making bribes abroad. We analyze the FCPA’s effects in a model of competition between a U.S. and foreign firm for contracts in a host country. If the FCPA only applies to the U.S. firm, it reduces that firm’s competitiveness and either increases bribery by the foreign firm or reduces overall investment. If the FCPA also applies to foreign firms, it reduces total bribery, and in host countries with high corruption levels, it increases total investment. The model suggests that the FCPA will deter bribery and stimulate investment while not disadvantaging U.S. firms if its enforcement is aimed at firms who engaged in bribery in highly corrupt countries and whose main competitors are also subject to the FCPA.
POINT/COUNTER-POINT—Links between traumatic brain injury and dementia remain poorly defined
Authors: Barr William B
Published: February 2020

There has been considerable public interest in the topic of traumatic brain injury (TBI) as a risk factor for development of late-life dementia. A review was performed on empirical studies examining the relationship between these two conditions. Although results from a number of studies clearly demonstrate that TBI is a positive risk factor for developing dementia, there are an equivalent number of studies that obtain inconclusive or negative findings. Inconsistencies across studies are often the result of methodological findings including the nature of the investigational design, choice of comparison groups, and criteria used to define cases. In many studies, the diagnosis of TBI is obtained retrospectively in a manner that is subject to bias. Accurate identification of dementia cases is often compromised by the use of inappropriately brief follow-up periods and variations in diagnostic methods. There remains no universally accepted neurobiological mechanism to explain the transition from acute TBI to the chronic effects of dementia. Studies of specialty populations, including athletes and military personnel are beset by secular and cohort effects, raising questions about the applicability of findings to the general population. No existing studies have been able to exclude the possible effects of confounding medical or lifestyle factors in facilitating the onset of dementia following TBI. Although the research findings suggest a general association between TBI and dementia, the specifics of the relationship remain poorly defined.
Defining “Ideal Abs” Through a Crowdsourcing-Based Assessment
Authors: Gould Daniel J , Shauly Orr , Qureshi Ali A , Stevens W Grant
Published: February 2020

Background

There were almost 12 million nonsurgical cosmetic procedures performed in the United States in 2016, which represented a 12% increase from the previous year, and popularity is expected to continue rising. Furthermore, nonsurgical fat reduction and body contouring have experienced a dramatic increase in popularity among both men and women. However, there has been very little work focused on the public’s perception of the ideal abdominal muscles.

Objectives

The authors sought to analyze patient perspectives on ideal abdominal contours and attitudes towards methods of improving the appearance of the abdomen.

Methods

A prospective cross-sectional study of 718 random volunteers recruited through Amazon Mechanical Turk was conducted. A survey instrument was administered to all study participants to assess the importance of ab symmetry, pec muscle definition, serratus muscle definition, and natural feel.

Results

Study participants across all ages, gender, ethnicity, and marital status indicated that a 6-pack was the ideal abdominal muscle count. They also rated the symmetry (61.06 ± 1.87) and natural feel of abs (60.72 ± 1.75) as the 2 most important aesthetic features in consideration of ideal abs. Study participants who reported exercising more than twice a week expressed a greater interest in nonsurgical procedures to achieve ideal abs (P = 0.007).

Conclusions

“Ideal abs” are 6 in number, symmetric, and feel natural. Millennials are much more willing to consider nonsurgical options to achieve ideal abs instead of surgery. Individuals who maintain a high level of fitness are, interestingly, more likely to want ideal abs and nonsurgical methods to achieve them.
Idarucizumab for the treatment of dabigatran-related nephropathy
Authors: Alsamarrai Ammar , Eaddy Nicola , Curry Elizabeth
Published: February 2020

Anticoagulant-related nephropathy (ARN) is a clinical syndrome of acute kidney injury in patients taking vitamin K antagonists or direct oral anticoagulants. It is associated with increased mortality and there is no specific treatment. We report the case of a 78-year-old man on dabigatran who developed macroscopic haematuria and acute kidney injury 2 weeks after mitral valve repair, reaching a peak creatinine of 415 µmol/L from a normal baseline, which was successfully treated with one course of idarucizumab. This case illustrates the efficacy of an anticoagulant reversal agent for the treatment of ARN.
Measurement of Erythrocyte Glucose-6-Phosphate Dehydrogenase Activity with a Centrifugal Analyzer
Authors: Catalano Edward W , Johnson George F , Solomon Harvey M
Published: February 2020

We describe two improved methods for determination of erythrocyte glucose-6-phosphate dehydrogenase activity. One method is an"enzyme-linked" procedure in which an excess of 6-phosphogluconate dehydrogenase is used to produce two moles of NADPH for each mole of glucose-6-phosphate oxidized. In the other method 2,3-diphosphoglycerate is used to inhibit the variable contribution of endogenous 6-phosphogluconate dehydrogenase to glucose-6-phosphate dehydrogenase activity in erythrocyte lysates. These assays require 100 µl of blood and are performed on a centrifugal analyzer in a final reaction volume of 410 µl at 37 °C. NADPH formation is monitored at 340 nm. Hemoglobin is measured as oxyhemoglobin in the same reaction mixture used to determine enzyme activity by changing the wavelength to 550 nm. Results are expressed as international units of glucose-6-phosphate dehydrogenase activity per gram of hemoglobin. The coefficient of correlation between "enzyme-linked" assay and "standard" assay was .992, the slope of the regression line was 1.07, and the intercept was at -0.76. When results of the "enzyme-linked" assay were compared to those of the "nonlinked" assay with added 2,3-diphosphoglycerate, the slope of the regression line was .994, the intercept 0.109, and the correlation coefficient .994.
Evaluation and clinical application of a dextran-charcoal method for measuring bound testosterone in human plasma.
Authors: Tcholakian R K , Jones G M , Sanborn B M , Rodriguez-Rigau L J , Reimondo G G
Published: February 2020

A method for rapidly determining bound and free testosterone in human plasma is evaluated and described, in which dextran-coated charcoal is used to separate bound and free testosterone. Intra- and inter-assay CV's were 1.9 and 3.8%, respectively. At least 50% of the "bound" testosterone was associated with species that behaved like sex steroid hormone-binding globulin on Sephadex G-25 chromatography and polyacrylamide gel electrophoresis. Bound and free testosterone concentrations were determined in normal men, normal women (during the menstrual cycle and during normal pregnancy), and in women with various degrees of hirsutism. We conclude that determining the circulating proportions of bound and free testosterone is helpful in the diagnostic evaluation of hirsutism in women, and in the investigation of normal and pathological conditions where androgen concentrations may be altered.
Simultaneous liquid-chromatographic quantitation of salicylic acid, salicyluric acid, and gentisic acid in urine.
Authors: Cham B E , Bochner F , Imhoff D M , Johns D , Rowland M
Published: February 2020

We have developed a specific and sensitive method for the determination of salicylic acid, salicyluric acid, and gentisic acid in urine. Any proteins present are precipitated with methyl cyanide. After centrifugation, an aliquot of the supernate is directly injected into an octadecyl silane reversed-phase chromatographic column, then eluted with a mixture of water, butanol, acetic acid, and sodium sulfate, and quantitated at 313 nm by ultraviolet detection according to peak-height ratios (with internal standard, o-methoxybenzoic acid) or peak heights (no internal standard). The method allows estimates within 25 min. Sensitivity was 0.2 mg/L for gentisic acid, and 0.5 mg/L for both salicyluric and salicylic acid (20-micro L injection volume); response was linear with concentration to at least 2.000 g/L for salicylic acid and metabolites. Analytical recovery of salicylic acid and metabolites from urine is complete. Intra-assay precision (coefficient of variation) is 5.52% at 7.5 mg/L for salicylic acid, 5.01% at 9.33 mg/L for salicyluric acid, and 3.07% at 7.96 mg/L for gentisic acid. Interassay precision is 7.32% at 7.51 mg/L for salicylic acid, 5.52% at 8.58 mg/L for salicyluric acid, and 3.97% at 8.32 mg/L for gentisic acid. We saw no significant interference in urine from patients being treated with various drugs other than aspirin.
Liquid-chromatographic determination of 5-fluorocytosine.
Authors: Miners J O , Foenander T , Birkett D J
Published: February 2020

We report a "high-performance" liquid-chromatographic method for measuring 5-fluorocytosine in plasma and cerebrospinal fluid. After deproteinization with trichloroacetic acid, the supernates are chromatographed on a reversed-phase (C18) column. Response to concentration is linear in the range of 5 to 200 mg/L, with ultraviolet detection at 276 nm. The assay requires only 0.1 mL of plasma, is reproducible, and may be performed in less than 12 min. 5-Fluorocytosine concentrations determined by this procedure correlated well with those obtained by spectrofluorometry, although the present method is more specific with no observable interference from co-administered amphotericin B and most other commonly encountered drugs, including salicylat:. This method is applicable to the routine therapeutic monitoring of pediatric and adult patients as well as to pharmacokinetic studies.
Immunoradiometric serum ferritin concentration compared with stainable bone-marrow iron as indices to iron stores.
Authors: Forman D T , Vye M V
Published: February 2020

Immunoradiometric analysis has made it possible to measure ferritin reliably in serum. The determination is a sensitive means of assessing body iron because concentrations of ferritin closely parallel the body's reticuloendothelial iron stores. The information provided is similar to that obtained from bone-marrow aspirates or biopsies stained for iron with Prussian Blue. Comparative studies indicate good correlation between iron content in the marrow and serum ferritin, except possibly in patients with leukemia and metastatic tumors to the bone marrow. The clinical value of the assay in relation to other indicators of iron status (i.e., hemoglobin, erythrocyte indices, serum iron and iron-binding capacity, and erythrocyte protoporphyrin) is in its specificity and sensitivity for assaying physiological iron stores.
Use of an alumina column in estimating total iron-binding capacity.
Authors: Starr R T
Published: February 2020

I describe a simple, rapid technique for saturating the transferrin in serum and then removing unbound (excess) iron. This technique involves use of an easily prepared column of basic chromatographic alumina and a saturating solution of ferric chloride in citric acid. This method, when compared with the magnesium carbonate method of Ramsay (Clin. Chim. Acta 2: 221, 1957) by regression analysis and tests of precision, showed a negative bias for results by the alumina technique with respect to the magnesium carbonate method.
Circulating CK-MB and CK-BB isoenzymes after prostate resection.
Authors: Kimler S C , Sandhu R S
Published: February 2020

We studied the effect of prostate resection on serum creatine kinase (EC 2.7.3.2) and lactate dehydrogenase (EC 1.1.1.27) isoenzymes in 22 patients. Two hours after their operations, two-thirds of these patients had increased total creatine kinase activity. The MB isoenzyme was demonstrated in sera of 66% of the patients and the BB isoenzyme in 76%. MB content varied from 1 to 7% of total creatine kinase activity, the average activity being 7.4 +/- 6 (SD) U/L. BB content varied from 1 to 29% of the total creatine kinase activity, the average activity being 8.5 +/- 5.4 U/L. No patients showed evidence of cardiac damage. In contrast to the enzyme changes associated with cardiac injury, MB isoenzyme seen after prostate resection is usually associated with the appearance of BB activity. In addition, the ratio of lactate dehydrogenase isoenzymes 1 and 2 was "inverted" in only five of the 33 patients, and appeared to corrlate with the degree of hemolysis in the postoperative sera. The prostate contains all three creatine kinase isoenzymes, BB predominating.
Spectrophotometric screening method for acetaminophen in serum and plasma.
Authors: Liu T Z , Oka K H
Published: February 2020

We describe a simple, economical procedure for rapidly detecting acetaminophen in serum or plasma. The method is based upon the reduction by the drug of ferric 2,4,6-tris(2-pyridyl)-s-triazine, at an acidic pH, to ferrous 2,4,6-tris(2-pyridyl)-S-triazine complex, which absorbs maximally at 593 nm. Absorbance and acetaminophen concentration are linearly related from 25 to 400 mg/L, and so therapeutic and toxic concentrations can be measured. The method is accurate; day-to-day CV's for two pooled control specimens (103 and 227 mg/L) were 4.4 and 6.6%. Correlation studies, with an established nitration method and with the free-radical diphenylpicrylhydrazyl dye method, showed correlation coefficients of 0.985 and 0.915, respectively. Of 25 commonly used drugs tested, only levodopa, oxyphenylbutazone, and phenylephrine interfere significantly. Interference from salicylate, salicylamide, and phenylbutazone was insignificant.
A fully automated, continuous-flow radioimmunoassay for methotrexate.
Authors: Kamel R , Landon J , Forrest G C
Published: February 2020

We describe a fully automated continuous-flow radioimmunoassay for methotrexate. [125I]Histamine-labeled methotrexate was used as tracer. Anti-methotrexate serum was coupled to a magnetizable solid-phase and the bound and free fractions were separated with an electromagnetic field. The assay is precise (CV less than 2.5%) and rapid (30 samples per hour), incubation volume is small (about 160 micro L), and incubation brief (10 min). The accurate timing inherent in the system obviates the need to attain equilibrium, so that assay of each sample takes only 15 min. The assay is sensitive (1--100 microgram/L). There is no significant carryover between samples of high and low concentration. Results by the automated method correlated well with those by both a manual assay in which the same reagents and separation technique are used (r - 0.99) and a competitive protein-binding assay (r = 0.96).
Semi-automated fluorometry of total estrogens in plasma during late pregnancy.
Authors: Goutte-Coussieu C , Sanchez D , Adessi G , Jayle M F
Published: February 2020

We describe a mechanized method for determining total estrogens in plasma during the last trimester of pregnancy. This method involves rapid enzymic hydrolysis, automatic extraction (in a tube) with cyclohexane/ethyl acetate, purification of the extracted material by anion-exchange chromatography on a disposable “mini-column” of Dowex AG1 X 2 (acetate form), and continuous-flow fluorometric quantification. Conditions of hydrolysis and extraction were studied. The mean within-day imprecision (CV) was 7% and between-day imprecision was 8.1%. Sensitivity was 75 nmol/L of plasma. Results are obtained in 4 h. The technique is quite suitable for routine determinations: 90 assays can be done by a team of three technicians in one working day.
Rate of decrease of glutamyltransferase and acid phosphatase activities in the human vagina after coitus.
Authors: Gohara W F
Published: February 2020

I studied the rate at which gamma-glutamyltransferase (EC 2.3.2.2) and acid phosphatase (EC 3.1.3.2) activities decrease in the healthy human vagina after coitus. Specimens from the coital and non-coital vagina, and from the rectum and buccal cavity, and pre-ejaculate lubricating fluid were also assayed for both enzymes. Prostatic acid phosphatase was determined with use of two substrates: thymolphthalein monophosphate and alpha-naphthyl phosphate (tartrate-inhibitable fraction). Glutamyltransferase was assayed with gamma-glutamyl-p-nitroanilide as substrate. All non-coital specimens were negative for glutamyltransferase activity; the activity of acid phosphatase varied with type of substrate and type of specimen. The equation y = a + (b/x) describes the decline in activity (y) of either acid phosphatase or glutamyltransferase in the vagina of healthy women post-coitally with time (x).
Continuous-flow fluorometry of low galactose concentrations in blood or plasma.
Authors: Henderson J M , Fales F W
Published: February 2020

Clearance of 0-100 mg/L concentrations of galactose from the blood depends on nutrient hepatic blood flow. We can measure such concentrations, which was not previously possible, by a continuous-flow method involving the use of galactose oxidase and peroxidase, the latter being coupled to a fluorogenic substrate, p-hydroxyphenylacetic acid. Interfering substances in the peroxidase reaction are removed by zinc/alkali precipitation. Sensitivity is maximized by using saturating concentrations of the enzymes and substrate. In prepared plasma test samples with galactose concentrations of 10, 40, 70, and 100 mg/L, the within-run CV's ranged from 2.1 to 8.6%, and day-to-day CV's from 2.2 to 17.2%, the largest CV's being for the 10 mg/L concentration. Normal subjects are shown to clear galactose more efficiently than subjects with moderate cirrhosis.
Comparison of radial immunodiffusion and laser nephelometry for quantitating some serum proteins.
Authors: Alexander R L
Published: February 2020

After quantitating immunoglobulins G, A, and M and complement C3c and C4 in serum by using a laser nephelometer coupled with a data processor, I compared these results with values obtained by an early-readout radial immunodiffusion method. Day-to-day precision was better for nephelometry than for radial immunodiffusion for all proteins analyzed. The average coefficient of variation was 6.0% for nephelometry and 9.9% for radial immunodiffusion. Comparison of these methods gave ranked correlation coefficients of 0.945, 0.981, 0.932, 0.803, and 0.792 for IgG, IgA, IgM, C3c, and C4, respectively. Nephelometry gave significantly higher values than radial immunodiffusion for IgG, IgA, IgM, and C3c, and significantly lower values for C4 (p less than 0.001). Part of this bias was found to be due to the equation programmed in the data processor for calculating the standard curves. Within 95% limits, nephelometry gave higher normal ranges than radial immunodiffusion for IgG, IgA, and IgM. Other possible factors that can produce this bias are discussed.
Room temperature radioassay for B12 with oyster toadfish (Opsanus tau) serum as binder.
Authors: Ithakissios D S , Kubiatowicz D O , Wicks J H
Published: February 2020

We describe a vitamin B12 radioassay with oyster toadfish (Opsanus tau) serum in which endogenous serum B12 is released from its protein complexes at room temperature with NaOH at pH 13.6. The radioassay is reproducible (CV 4.9% within assay, 8.4% between assays) and sensitive (10 ng/L) and requires minimum manipulations. Assay accuracy is unaffected by serum protein.
Improved direct specific determination of serum iron and total iron-binding capacity.
Authors: Ceriotti F , Ceriotti G
Published: February 2020

Serum iron is released from transferrin and reduced at pH 1.7 by treating serum with a 10 g/L ascorbic acid solution in 0.1 mol/L HCl. When ferrozine is added to this reagent, it forms a complex with iron that is as intensely colored as at higher pH values, and under these conditions no turbidity is produced. The second major interference, that from copper, is eliminated by adding 1 g of thiosemicarbazide per liter, which at a low pH forms a stable, uncolored complex with copper without affecting the reaction of ferrozine with iron.
False-negative results for urinary phenothiazines and imipramine in Forrest's qualitative assays.
Authors: James G P , DJang M H , Hamilton H H
Published: February 2020

When a series of patients' urine samples supplemented in vitro with chlorpromazine or imipramine was assayed with the Forrest qualitative assays, we observed an occasional false-negative result, which we found was attributable to interference by ascorbic acid. It interferes with the reagent, not with the analytes, in both assays. We easily eliminated this interference with the phenothiazine test by using an anion-exchange resin. Eliminating the interference with the assay for imipramine, however, is more difficult; false-negative results can be obtained even after ion-exchange chromatography if the imipramine concentration is less than 50 mg/L.
Radioimmunoassay of thyroxine in 10 microliters of serum, with use of aggregated antithyroxine antibodies.
Authors: Collins S , Brooks M , Bermes E W
Published: February 2020

We describe a sensitive radioimmunoassay for rapidly determining the concentration of thyroxine in 10 microL of human serum. Aggregated antithyroxine antibodies are used to separate bound and free hormone. This speeds the assay and economizes on reagents without loss of sensitivity, specificity, or precision. Results for normal subjects and patients with thyroid disease agree well with those obtained by other, well-established techniques.
Alkaline phosphatase of high and low molecular mass in human serum and bile: a comparative study of kinetic properties.
Authors: Crofton P M , Smith A F
Published: February 2020

We studied the kinetic properties of high- and low-molecular-mass forms of alkaline phosphatase purified from serum and bile, to clarify their interrelationships. They were found to share virtually identical kinetic properties, and to obey the same general kinetics as the liver-derived isoenzyme from serum and the low-molecular-mass isoenzyme from bile with regard to optimum conditions of assay, activation by magnesium ions, inhibition by L-homoarginine, inhibition by nickel and zinc ions, and inactivation by urea. Most of the characteristics such as Km (at low magnesium ion concentrations), Ki for L-homoarginine, and half-life for urea inactivation, were closely similar for low- and high-molecular-mass alkaline phosphatase. We conclude that these forms of alkaline phosphatase in plasma and bile are closely related. We discuss the possible nature of this relationship.
Methods for ligand-receptor assays in clinical chemistry.
Authors: Smith R G , Sestili M A
Published: February 2020

This is intended to be a practical review for the clinical chemist of the laboratory procedures most commonly used to quantitate hormone receptors in various cellular fractions. These procedures include use of charcoal adsorption and hydroxylapatite for intracellular receptors and of centrifugation and filtration for membrane receptors. We discuss the use of the Scatchard analysis to establish the steroid-receptor affinity and the quantity of steroid-receptor binding sites. Both pre- and post-labeled sucrose density gradient methods are outlined. One section is devoted to the direct and indirect methods used in nuclear “exchange” assays. Basic theory underlying each assay is presented, but, more importantly, we assess the advantages and disadvantages of each procedure. On the basis of this information, one may decide which assay is best suited for a particular laboratory and (or) specimen.
Performance of a radiometer transcutaneous oxygen monitor in a neonatal-intensive-care unit.
Authors: Graham G , Kenny M A
Published: February 2020

We evaluated the performance of the Radiometer TCM-1 Transcutaneous Oxygen Monitor in a Class III neonatal-intensive-care unit during an 11-month clinical trial (in excess of 4000 h) in which we monitored 115 infants ranging in gestational age from 25 to 43 weeks and in birthweight from 595 to 4220 g. In vitro transcutaneous partial pressure of oxygen (ptcO2) measurements were accurate within 1% of the theoretical value and precise (1.4% CV at 156 mmHg) at 44 degrees C. Determinations at other temperature were less accurate except in rare instances when specific patient-associated ptcO2/paO2 bias was identified. In vitro comparison of ptcO2 (y) and arterial partial pressure of oxygen (paO2) (x) measurements agreed well (y = 0.90x + 6.9, r = 0.94) except when infants were less than 24 h old. In this latter group the ptcO2/paO2 ratio usually exceeded 1.0 and fluctuated unpredictably. ptcO2 measurements on infants less than 24 h old had to be interpreted cautiously. In general, the ptcO2 and paO2 measurements agreed sufficiently well for the physicians to use them as the basis for directing patient care.
Interference of imferon in colorimetric assays for iron.
Authors: Huisman W
Published: February 2020

Imferon (Merrell-National), an iron-dextran complex, is widely used in patients with iron deficiency. It is present in the circulation in appreciable amounts for two to three weeks after administration and interferes with all tested colorimetric iron assays, both with and without deproteinization. The amount of the plasma Imferon iron interference depends primarily on the choice of reductant. With dithionite it is essentially 100%. In the presence of ascorbic acid and hydroxylamine, the interference depends also on assay conditions, especially temperature, but also incubation time and pH. The minimum interference in a homogeneous assay was about 3%. The relative amount of interference from hemoglobin iron under the various assay conditions is different from that of Imferon iron. In the presence of a reducing agent, the dextran-iron complex decomposes--instantaneously with dithionite, and gradually with sulfite, ascorbic acid, and hydroxylamine. The freed iron becomes dialyzable, can react with bathophenanthroline, and elutes on a Sephadex G-50 or G-15 column in the same fractions as an ammonium ferrous sulfate.
Stability of standard curves prepared for EMIT homogeneous enzyme immunoassay kits stored at room temperature after reconstitution.
Authors: Bach P R , Larsen J W
Published: February 2020

We examined the stability of standard curves obtained with use of homogeneous enzyme immunoassay reagents (EMIT; Syva Corp., Palo Alto, CA) for assay of lidocaine, procainamide, N-acetylprocainamide, gentamicin, and theophylline, when stored at room temperature (23-24 degrees C) after reconstitution of the lyophilized materials. Standards were run and curves obtained for as long as 16 days after reconstitution. All standard curves were acceptable, according to the criteria specified in Syva product literature. Absorbance changes for all calibrators, including the zero calibrator, increased gradually with time. Increases of non-zero calibrators were largely offset by a parallel increase in the zero calibrator, such that the quantity delta A--delta A0 was very nearly constant with time. Standard curves based on the quantity delta A--delta A0 can be used for longer than curves based only on delta A.
Measuring thyroxine and thyrotropin simultaneously in a dried blood sample on filter paper, to screen for neonatal hypothyroidism.
Authors: Nagataki S , Ishibashi K , Ohsawa R , Suwa S , Tsukamoto N , Takahashi T , Obara Y , Liao Y Y
Published: February 2020

We have developed a highly sensitive radioimmunoassay of thyroxine and thyrotropin for mass screening for neonatal hypothyroidism. This assay involves a single disc (3 mm diameter) of dried blood on filter paper. The minimum detectable concentrations are 15 pg/tube (10 microgram/L) for thyroxine and 15 nano-int. units/tube (10 milli-int. units/L) for thyrotropin; intra- and interassay CV’s are < 15% in both assays. The high sensitivity of this method is due to use of labeled thyroxine with high specific activity (3 kCi/g) and of an anti-thyrotropin serum with high affinity (Keq = 7.8 × 10(11) L/mol). With this method, 11337 newborns were screened; a follow-up study revealed that only newborns with both high thyrotropin and low thyroxine concentrations had permanent hypothyroidism. We conclude that this method is sensitive, simple, and reliable and that the recall rate with this method is much lower than that of tests for measuring thyroxine or thyrotropin alone.
Problems in radioimmunoassay of human lutropin with commercially available reagents.
Authors: Hammond J E , Phillips J C , Straight C B , Hammond M G
Published: February 2020

To evaluate five commercially available reagent sets supplied for the radioimmunoassay of lutropin, we determined whether there was parallelism between the curve given by dilutions of the standards supplied by the manufacturers, by dilutions of a serum pool, and by dilutions of a standard preparation from human pituitaries, LER-907. These studies demonstrated significant analytical problems with three of the five sets. We conclude that each user should carefully evaluate all commercially available radioimmunoassays for lutropin (and, by inference, for other peptide hormones) before use.
Total serum cholesterol by isotope dilution/mass spectrometry: a candidate definitive method.
Authors: Cohen A , Hertz H S , Mandel J , Paule R C , Schaffer R , Sniegoski L T , Sun T , Welch M J , White E
Published: February 2020

We describe a highly accurate and precise method for determination of total cholesterol in serum by isotope dilution/mass spectrometry. The method was developed for a Study Group of the Committee on Standards of the American Association for Clinical Chemistry, for use in establishing the accuracy of a candidate reference method for total cholesterol, and fulfills their criteria for a definitive method. Cholesterol-d7 is added to serum, with the weight ratio of cholesterol-d7 to total serum cholesterol kept near to 1:1. The esters are hydrolyzed and the cholesterol is separated and converted into the trimethylsilyl ether derivative for measurement by combined gas chromatography/mass spectrometry. The intensity ratio of the molecular ions at m/z 465 and 458 is measured for each sample and for two calibration mixtures, according to a prescribed bracketing protocol. A weight ratio for the sample is obtained by linear interpolation of the ion-intensity ratios, and the total cholesterol is then calculated. The method was applied four times over several weeks to each of five serum pools. Statistical analysis involving consideration of both replication error and variability between weeks gave a coefficient of variation for a single measurement of 0.36%. The absence of interferences in the method was demonstrated by measurements at several other masses.
Serum gastrins in Zollinger-Ellison syndrome: identification of localized disease.
Authors: Johnson J A , Fabri P J , Lott J A
Published: February 2020

We determined the relative concentrations of gastrin molecular species in serum samples from 21 patients with Zollinger-Ellison syndrome with localized gastrinoma (n = 11) or gastrinoma with hepatic metastases (n = 10). Gastrin molecular species were separated by gel-filtration chromatography and quantitated by radioimmunoassay with a gastrin antiserum produced in our laboratory. The percentage gastrin-17 of the total gastrin in the two groups differed significantly (nonparametric Wilcoxon rank test; p less than 0.01). Patients with the Zollinger-Ellison syndrome with apparently localized gastrinoma had a lower percentage of G- 17 (7.6%, SEM 1.6%) than did patients with gastrinoma with hepatic metastases (31.1%, SEM 6.1%). This procedure may be useful in the early classification of tumors in patients with Zollinger-Ellison syndrome.
On-line liquid-chromatographic analysis for drugs in serum with the Technicon "FAST-LC" system: performance data for theophylline and for four commonly used anticonvulsants and their metabolites.
Authors: Dolan J W , van der Wal S , Bannister S J , Snyder L R
Published: February 2020

We describe a new instrument for use in assay of therpeutic drugs in serum by "high-performance" liquid chromatography, the "FAST-LC" system (Technicon). Serum samples are aspirated directly into the unit, extracted with solvent, and the evaporated and redissolved extract is injected onto a chromatographic column. We illustrate the performance of the system by assays in serum for theophylline and four anticonvulsants (primidone, phenobarbital, phenytoin, and carbamazepine) plus two of their active metabolites (phenylethylmalonamide and carbamazepine epoxide). For theophylline, final chromatograms are monitored at 270 nm, at analysis rates of 10/h. Concentration and absorbance are linearly related from 0 to 130 mg of theophylline per liter. For the anticonvulsants, chromatograms are monitored at 200 nm, at analysis rates of 7.5/h. The six individual determinations are each linear beyond the therapeutic range. For both drug panels, day-to-day CV's were 4 to 6%. Results correlate well with those by enzyme immunoassay. A total sample volume of 150 microL is required.
A semi-automatic enzymic method for estimating urinary oxalate.
Authors: Yriberri J , Posen S
Published: February 2020

A two-enzyme method is presented for estimating urinary oxalate by continuous-flow analysis. Oxalate is decarboxylated, yielding formate, which is subsequently oxidized in the presence of NAD+, yielding NADH. The NADH, measured colorimetrically, is proportional to the amount of oxalate originally present in the sample. Urine is pretreated by precipitation of the oxalate and extraction of the precipitate in citrate buffer. A correction factor for the extraction efficiency is given by the recovery of [U-14C]oxalic acid added to aliquots of the 24-h urine specimen. The normal range obtained by this method was 0.20 to 0.52 mmol/24h (18 to 47 mg/24h) with a mean value of 0.37 mmol/24 h (33 mg/24h). The between-assay CV was 7.6% (n = 12), within-assay CV 3.2% (N = 25). Unlabeled oxalate (0.5 and 1.0 mol/L) added to 28 urine samples gave a mean analytical recovery of 95% (SD 10%).
In vivo distribution of proteins within a single cell.
Authors: Austerberry C F , Paine P L
Published: February 2020

Using the oocyte of Xenopus laevis, we present an experimental system, involving two-dimensional gel electrophoresis, for measuring unambiguously the nucleocytoplasmic distribution of proteins within a living cell.
Temporal variability modulates pH impact on larval sea urchin development
Authors: Chan Kit Yu Karen , Tong Chun Sang Daniel
Published: February 2020

Coastal organisms reside in highly dynamic habitats. Global climate change is expected to alter not only the mean of the physical conditions experienced but also the frequencies and/or the magnitude of fluctuations of environmental factors. Understanding responses in an ecologically relevant context is essential for formulating management strategies. In particular, there are increasing suggestions that exposure to fluctuations could alleviate the impact of climate change-related stressors by selecting for plasticity that may help acclimatization to future conditions. However, it remains unclear whether the presence of fluctuations alone is sufficient to confer such effects or whether the pattern of the fluctuations matters. Therefore, we investigated the role of frequency and initial conditions of the fluctuations on performance by exposing larval sea urchin Heliocidaris crassispina to either constant or fluctuating pH. Reduced pH alone (pH 7.3 vs 8.0) did not affect larval mortality but reduced the growth of larval arms in the static pH treatments. Changes in morphology could affect the swimming mechanics for these small organisms, and geometric morphometric analysis further suggested an overall shape change such that acidified larvae had more U-shaped bodies and shorter arms, which would help maintain stability in moving water. The relative negative impact of lower pH, computed as log response ratio, on larval arm development was smaller when larvae were exposed to pH fluctuations, especially when the change was less frequent (48- vs 24-h cycle). Furthermore, larvae experiencing an initial pH drop, i.e. those where the cycle started at pH 8.0, were more negatively impacted compared with those kept at an initial pH of 7.3 before the cycling started. Our observations suggest that larval responses to climate change stress could not be easily predicted from mean conditions. Instead, to better predict organismal performance in the future ocean, monitoring and investigation of the role of real-time environmental fluctuations along the dispersive pathway is key.
Cardiac magnetic resonance radiomics: basic principles and clinical perspectives
Authors: Raisi-Estabragh Zahra , Izquierdo Cristian , Campello Victor M , Martin-Isla Carlos , Jaggi Akshay , Harvey Nicholas C , Lekadir Karim , Petersen Steffen E
Published: February 2020

Radiomics is a novel image analysis technique, whereby voxel-level information is extracted from digital images and used to derive multiple numerical quantifiers of shape and tissue character. Cardiac magnetic resonance (CMR) is the reference imaging modality for assessment of cardiac structure and function. Conventional analysis of CMR scans is mostly reliant on qualitative image analysis and basic geometric quantifiers. Small proof-of-concept studies have demonstrated the feasibility and superior diagnostic accuracy of CMR radiomics analysis over conventional reporting. CMR radiomics has the potential to transform our approach to defining image phenotypes and, through this, improve diagnostic accuracy, treatment selection, and prognostication. The purpose of this article is to provide an overview of radiomics concepts for clinicians, with particular consideration of application to CMR. We will also review existing literature on CMR radiomics, discuss challenges, and consider directions for future work.
Craniofacial, oral, and cervical morphological characteristics in Japanese patients with Apert syndrome or Crouzon syndrome
Authors: Kobayashi Yukiho , Ogura Kenji , Hikita Rina , Tsuji Michiko , Moriyama Keiji
Published: February 2020

Background and objectives

Mutations in the fibroblast growth factor receptor 2 (FGFR2) gene are responsible for both Apert syndrome (AS) and Crouzon syndrome (CS). These diseases share phenotypic characteristics, including midfacial hypoplasia and premature fusion of the calvarial suture(s). Given the extensive range of craniofacial growth and developmental abnormalities, management of these patients requires a multidisciplinary approach. This study aimed to compare craniofacial, oral, and cervical morphological characteristics in Japanese orthodontic patients with AS or CS.

Subjects and methods

Lateral cephalograms, orthopantomograms, dental casts, medical interview records, facial photographs, and intraoral photographs of 7 AS patients and 12 CS patients on initial visits were used in this study. Cephalometric analyses were performed, and standard scores were calculated based on age- and sex-matched Japanese standard values.

Results

Cephalometric analysis revealed that AS patients had significantly more severe maxillary hypoplasia in two dimensions and increased clockwise mandibular rotation. Additionally, cleft of the soft palate, anterior open bite, severe crowding in the maxillary dental arch, and congenitally missing teeth occurred more frequently among AS patients. Multiple fusions between cervical vertebrae C2, C3, C5, and C6 were observed in the AS patients.

Limitations

Small sample size.

Conclusions/implications

Our study shows that AS patients have more severe craniofacial and maxillofacial deformities than CS patients.
Change Is Good for the Brain: Activity Diversity and Cognitive Functioning Across Adulthood
Authors: Lee Soomi , Charles Susan T , Almeida David M
Published: February 2020

Objectives

Participating in a variety of daily activities (i.e., activity diversity) requires people to adjust to a variety of situations and engage in a greater diversity of behaviors. These experiences may, in turn, enhance cognitive functioning. This study examined associations between activity diversity and cognitive functioning across adulthood.

Method

Activity diversity was defined as the breadth and evenness of participation in seven common daily activity domains (e.g., paid work, time with children, leisure, physical activities, volunteering). Participants from the National Survey of Daily Experiences (NSDE: N = 732, Mage = 56) provided activity data during eight consecutive days at Wave 1 (W1) and Wave 2 (W2) 10 years apart. They also provided cognitive data at W2.

Results

Greater activity diversity at W2 was associated with higher overall cognitive functioning and higher executive functioning at W2. Individuals who increased activity diversity from W1 to W2 also exhibited higher scores in overall cognitive functioning and executive functioning at W2. Overall cognitive functioning, executive functioning, and episodic memory were better in those who had higher activity diversity at both waves, or increased activity diversity from W1 to W2, compared to those who had lower activity diversity or decreased activity diversity over time.

Discussion

Activity diversity is important for cognitive health in adulthood. Future work can study the directionality between activity diversity and cognitive functioning and underlying social and neurological mechanisms for these associations.