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Background: To investigate the validation of phenol red thread (PRT) test in a Chinese population by evaluating the intraobserver repeatability and interobserver reproducibility, determining correlations between the PRT test and other dry eye disease (DED) parameters including tear meniscus height (TMH) and Schirmer I test, and testing the accuracy of diagnosing DED when using the PRT test alone., Methods: A total of 108 eyes were involved in this prospective and diagnostic study, and were divided into two groups (with and without DED). Each subject underwent a series of ocular surface examinations, including Ocular Surface Disease Index (OSDI) questionnaire, non-invasive tear breakup time (NIBUT), tear meniscus height (TMH) assessment, PRT test, fluorescein tear breakup time (FBUT), corneal fluorescein staining and Schirmer I test., Results: In the experimental group and the control group, the intra-class correlation coefficients (ICCs) of the repeatability were 0.747 and 0.723, respectively (all P < 0.05). The ICCs of the reproducibility in both groups were 0.588 and 0.610, respectively (all P < 0.05). The PRT test correlated weakly with the Schirmer I test and the tear meniscus height, with Spearman coefficients of 0.385 and 0.306, respectively (all P < 0.05). The PRT test is available to diagnose DED, with an area under the curve of 0.806 and a Youden index of 0.556 at the cutoff point of 8.83 mm., Conclusions: The PRT test can provide patients a comfortable, timesaving and less irritating approach to screening and diagnosing DED compared to Schirmer I test., (© 2023. The Author(s).)

In this study, horseradish peroxidase (HRP) was immobilized for the first time on Ca alginate-starch hybrid beads and employed for the biodegradation of phenol red dye. The optimal protein loading was 50 mg/g of support. Immobilized HRP demonstrated improved thermal stability and maximum catalytic activity at 50 °C and pH 6.0, with an increase in half-life (t 1/2 ) and enzymatic deactivation energy (E d ) compared to free HRP. After 30 days of storage at 4 °C, immobilized HRP retained 109% of its initial activity. Compared to free HRP, the immobilized enzyme exhibited higher potential for phenol red dye degradation, as evidenced by the removal of 55.87% of initial phenol red after 90 min, which was 11.5 times greater than free HRP. In sequential batch reactions, the immobilized HRP demonstrated good potential efficiency for the biodegradation of phenol red dye. The immobilized HRP was used for a total of 15 cycles, degrading 18.99% after 10 cycles and 11.69% after 15 cycles, with a residual enzymatic activity of 19.40% and 12.34%, respectively. Overall, the results suggest that HRP immobilized on Ca alginate-starch hybrid supports shows promise as a biocatalyst for industrial and biotechnological applications, particularly for the biodegradation of recalcitrant compounds such as phenol red dye., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier B.V.)

The potential of coordination polymers (CPs) as a host of integrating multiple guest species to construct a fluorescence resonance energy transfer (FRET) nanoprobe was demonstrated. The ZnCPs built from zinc(II) and adenine was employed as a model of CPs to integrate carbon dot (CD) and phenol red (PR) for producing the FRET nanoprobe (CD/PR@ZnCPs). Benefiting from the confinement effect of ZnCPs, the integrated CD and PR can be brought in close proximity to favor the occurrence of FRET process from CD to PR, which leads to the quenching of CD fluorescence. However, the FRET process was disrupted upon the red-shift of PR absorption from 428 to 562 nm in alkaline medium, and consequently switches on the fluorescence of CD/PR@ZnCPs. Based on this finding, by utilizing urease to hydrolyze urea and mediate medium pH, a turn-on fluorescent method was established for the detection of urease activity. This fluorescent method has a linear response that covers 5 to 150 U/L urease with a detection limit of 0.74 U/L and exhibits an excellent selectivity over other enzymes. The successful determination of urease in saliva samples demonstrates the applicability of the fluorescent nanoprobe in complex biological matrix., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Exploring new and high efficiency mimic enzymes is a vital and novel strategy for antibacterial application. Haloperoxidase-like enzymes have attracted wide attention thanks to their amazing catalytic property for hypohalous acid generation from hydrogen peroxide and halides. However, few materials have displayed halogenating catalytic performance until now. Herein, we synthesized N-doped C/CeO 2 (N-C/CeO 2 ) composite materials by a combination of the liquid and solid-state method. N-C/CeO 2 can possess haloperoxidase-like catalytic activity by catalyzing the bromination of organic signaling compounds (phenol red) with H 2 O 2 at a wide range of temperatures (20 °C to 55 °C), with a solution color changing from yellow to blue. Meanwhile, it exhibits high catalytic stability/recyclability in the catalytic reaction. The synthesized N-C/CeO 2 composite can effectively catalyze the oxidation of Br - with H 2 O 2 to produce HBrO without the presence of phenol red. The produced HBrO can resist typical marine bacteria like Pseudomonas aeruginosa . This study provides an efficient biomimetic haloperoxidase and a novel sustainable method for antibacterial application.

Dehydration has always been a confusing problem for a hydrogel exposed to air, which restricts its application in practical detection. While an ionogel with unique properties can lock water molecules efficiently due to its low vapor pressure, the design and development of an ionogel with excellent water-locking properties and stability to achieve satisfactory detection are thus highly desirable. In this work, a pH-sensitive, stretchable, antibacterial, and stable ionogel artificial tongue was fabricated through dual cross-linking. The artificial tongue consisted of MXene as a cross-linking agent, phenol red as an indicator, gelatin, N-(2-hydroxyethyl) acrylamide, and 1-butyl-3-methylimidazolium chloride as the three-dimensional polymer network. A small quantity of MXene was used as a cross-linker the first time to promote the initiator in the system to generate free radicals, accelerating the reaction process and the multilevel linkage among the polymers. Meanwhile, the indicator phenol red was introduced into the ionogel successfully for the first time, showing great stability in 5 weeks. After evaluation by the Brand-Altman analysis, it was found that the method of pH measurement using ionogels had good consistency with the pH meter measurement method. Additionally, the prepared ionogel presented excellent water retention, mechanical stretchability, antibacterial property, and stability, as well as good test results in the test of artificial simulated saliva, demonstrating great potential in clinical applications.

A highly sensitive electrochemical methodology for end-point detection of loop-mediated isothermal nucleic acid amplification reactions was developed. It is based on the oxidation process of phenol red (PR), commonly used as a visual indicator. The dependence of its redox process on pH, which changes during amplification, allows performing quantitative measurements. Thus, the change in the oxidation potential of PR during the amplification is used, for the first time, as the analytical signal that correlates with the number of initial DNA copies. As a proof-of-concept, the amplification of the pneumolysin gene from Streptococcus pneumoniae , one of the main pathogens causing community-acquired pneumonia, is performed. Combination of isothermal amplification with electrochemical detection, performed on small-size flexible electrodes, allows easy decentralization. Adaptation to the detection of other pathogens causing infectious diseases would be very useful in the prevention of future epidemics.

Phenol red and PEG-4000, the usual non-absorbable indicators, have non-negligible absorption problems in measuring water flux. mPEG-PR, combined phenol red with mPEG-4000, was first synthesized and could decrease absorption. However, its application has not been confirmed. The purpose of this study was to explore the applicability of mPEG-PR as a novel non-absorption indicator in the in situ single-pass intestinal perfusion (SPIP) experiment. Six model drugs (atenolol ranitidine, ibuprofen, ketoprofen, antipyrine, hydrochlorothiazide) were used to compare the accuracy of four measuring methods including phenol red, mPEG-PR, gravimetric, and non-corrected methods of correcting intestinal fluid transport. Moreover, we evaluated the correlations between the effective permeability coefficients (P eff ) in rat and fraction dose absorbed (F abs ) in human, P eff in human, and apparent permeability coefficients (P app ) by the Ussing Chamber system using human tissue. Among these methods, mPEG-PR was the most reliable approach, which avoided the absorption of phenol red method and mucous shedding or water evaporation of gravimetric method. An excellent correlation was obtained between the P eff of rat and F abs of human. Our results of this study indicated that mPEG-PR was a stable and accurate non-absorbable indicator to correct water flux in the in situ SPIP model, which could be developed to predict the human F abs ., (Copyright © 2022. Published by Elsevier B.V.)

The aim of this study was to determine, in the diet-induced obesity model in rats, the potential of Guanabenz to reduce body weight and ameliorate some metabolic disturbances. Obesity was induced in rats by a high-fat diet. After 10 weeks, rats were treated intraperitoneally with Guanabenz at the two doses: 2 or 5 mg/kg b.w./day, once daily for 25 days. The spontaneous activity of rats was measured for 24 h on the 1st and 24th day of the Guanabenz treatment with a special radio-frequency identification system. Gastric emptying was measured in intragastric phenol red-treated mice by measuring the color of the stomach homogenate 30 min after phenol red administration. Intraperitoneal administration of Guanabenz for 25 days to obese rats resulted in a significant decrease in body weight compared to the baseline values (about 11% at a dose of 5 mg/kg). Both body weight and the amount of adipose tissue in the groups receiving Guanabenz decreased to the levels observed in the control rats fed only standard feed. The anorectic effect occurred in parallel with a reduction in plasma triglyceride levels. We also confirmed the beneficial effect of Guanabenz on plasma glucose level. The present study demonstrates that the administration of Guanabenz strongly inhibits gastric emptying (about 80% at a dose of 5 mg/kg). Guanabenz can successfully and simultaneously attenuate all the disorders and risk factors of metabolic syndrome: hypertension, hyperglycemia, obesity, and dyslipidemia. However, the exact cellular mechanisms of its action require further research., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Identification of α0-thalassemia (SEA and THAI deletions) is essential in preventing and controlling of severe thalassemia diseases. We have developed the LAMP colorimetric assays for the detection of these two thalassemia defects and validated them in population screening and prenatal diagnosis., Methods: Three LAMP colorimetric assays specific for α0-thalassemia (SEA deletion), α0-thalassemia (THAI deletion) and normal DNA sequence were developed. These assays were validated on 341 subjects who had initial thalassemia screening positive and various thalassemia genotypes. Prenatal diagnosis of α0-thalassemia (SEA deletion) was done on 33 fetuses at risk of having Hb Bart's hydrops fetalis syndrome., Results: The LAMP colorimetric assays for α0-thalassemia (SEA and THAI deletions) could be clearly interpreted by naked eyes. The assay for α0-thalassemia (SEA deletion) showed a 100% (62/62 x 100) sensitivity and 98.2% (274/279 x 100) specificity whereas, that of the α0-thalassemia (THAI deletion) showed 100% (1/1 x 100) sensitivity and 99.7% (339/340 x 100) specificity. We obtained a 100% concordant prenatal diagnosis results using LAMP assays of α0-thalassemia (SEA deletion) in 33 fetuses as compared to the conventional PCR analysis., Conclusions: The LAMP colorimetric assays developed are simple, rapid, and do not require sophisticated equipment. Inclusion of the LAMP tests in the existing screening protocol significantly reduce the screening cost and the molecular analysis workload, which should prove useful in the prevention and control program of hemoglobinopathies in the region., Competing Interests: The authors have declared that no competing interests exist.

Purpose: Noninvasive analyses of tear fluid from humans and animal models in clinical and research settings most commonly use absorbent material for collection and processing. Still, the impact of these analytical techniques on tear chemical analyses remains largely unknown. The purpose of this study was to quantify the impacts of phenol red thread fiber-based tear sample collection and processing on the primary amine content., Methods: Human tears were collected by placing the folded end of phenol red thread on the palpebral conjunctiva of the right eye for 20 seconds. The wetted thread was then processed using elution or extraction, and capillary electrophoresis with light-emitting diode-induced fluorescence detection was used for analysis and quantitation., Results: Distinct processing methods impacted tear analysis differently. Primary amines adsorbed onto the thread partitioned in a chromatographic manner and thus any single portion of the wetted thread might not be representative of the whole sample. Quantitative assessment of five small molecule standards after on-thread processing showed significant overestimation of the actual concentration, with increased accuracy for larger volume samples. Yet collection of larger tear volumes introduced error in volume determination owing to evaporation and reduced small molecule separation resolution., Conclusions: These results indicated that absorption-based tear fluid collection and processing significantly alter chemical content analysis, suggesting that the impacts of methods used should be regularly evaluated to standardize results drawn from different studies., Translational Relevance: This study identifies potential inconsistencies and inaccuracies in tear analyses that are widespread across the published literature and clinical care., Competing Interests: Disclosure: A. Barmada, None; S.A. Shippy, None, (Copyright 2020 The Authors.)

Objectives: The strip meniscometry test (SMT) is a novel method for quantitative measurement of tear volume with only five seconds. We aimed to evaluate clinical correlations of SMT with the gold standard Schirmer tear test (STT) and phenol red thread test (PRT) in dogs, including normal and tear-deficient eyes., Animals Studied: Left eyes from 621 outpatient dogs with and without ocular disorders were evaluated., Procedures: Each subject underwent SMT, PRT, and STT without topical anesthesia in the described order with five-minute intervals. The total population was divided into four groups by classifying tear deficiency severity based on STT results: "severe" (0-5 mm/min), "moderate" (6-10 mm/min), "subclinical" (11-14 mm/min), and "normal" (15 or more mm/min)., Results: The strongest correlation coefficient was found between SMT-STT (0.676), followed by PRT-STT (0.637) and SMT-PRT (0.600) pairs. Mean(SD) scores of SMT, PRT, and STT in total population were 9.47 (4.08) mm/5 s, 33.30 (8.52) mm/15 s, and 16.47 (7.01) mm/min. Significant differences were found among STT-classified groups, both using SMT and PRT results. Receiver operating characteristic (ROC) curves revealed that SMT better agreed with STT than PRT; agreement increased with increasing STT severity. A cutoff for SMT was identified at 10 mm/5 s to discriminate normal eyes from tear-deficient eyes, yielding high sensitivities and acceptable specificities., Conclusions: SMT could be superior to PRT for discriminating tear-deficient eyes. The high sensitivity of SMT could be useful as an initial diagnostic tool to rule out normal eyes with the short testing time., (© 2019 American College of Veterinary Ophthalmologists.)

To evaluate tear production in the common mynah ( Acridotheres tristis ) using the phenol red thread test (PRTT) and to make a comparison of measurements with the PRTT placed in the fornices of lower and upper eyelids, tear production of both eyes in 22 healthy adult captive mynah birds was evaluated. After positioning of threads in the fornices of upper and lower eyelids, the PRTT values of the birds were 17.5 ± 3.1 mm/15 s and 19.2 ± 2.5 mm/15 s, respectively. A significant difference was found between PRTT values for upper eyelids and lower eyelids (P = 0.01). This study provides novel data for normal reference ranges of PRTT values in healthy common mynah birds and shows that a difference is found depending on where the PRTT thread is placed.

Falconiformes are active searchers and hunters that require visual precision to catch their prey and survive in the wild. Despite this, ocular disease is likely to be underdiagnosed in these species, at least in part because of limited proven diagnostic methods and lack of published scientific data. Tear film deficiency is recognized as an important ocular surface disease in dogs but has not been well evaluated in birds. To evaluate the phenol red thread (PRT) tear test as an alternative method to the Schirmer tear test (STT) for determining tear production in Falconiformes, we assessed the PRT tear test twice for each eye in 21 birds from the genus Falco. The mean PRT test values for the right (OD) and left (OS) eyes were OD=30.2±4.6 mm/15 s and OS=29.1±3.7 mm/15 s, with an overall PRT test value for both eyes (OU) of 30.6±4.2 mm/15 s. Good reproducibility was seen with the PRT test as shown by the strong positive correlation between the first and second tests in the birds. The PRT test method provides repeatable results that are easy to obtain, easy to read, and achieved under the same conditions as the STT.

The aim of the present study was to develop a method for water flux reabsorption measurement in Doluisio's Perfusion Technique based on the use of phenol red as a non-absorbable marker and to validate it by comparison with gravimetric procedure. The compounds selected for the study were metoprolol, atenolol, cimetidine and cefadroxil in order to include low, intermediate and high permeability drugs absorbed by passive diffusion and by carrier mediated mechanism. The intestinal permeabilities (Peff) of the drugs were obtained in male and female Wistar rats and calculated using both methods of water flux correction. The absorption rate coefficients of all the assayed compounds did not show statistically significant differences between male and female rats consequently all the individual values were combined to compare between reabsorption methods. The absorption rate coefficients and permeability values did not show statistically significant differences between the two strategies of concentration correction. The apparent zero order water absorption coefficients were also similar in both correction procedures. In conclusion gravimetric and phenol red method for water reabsorption correction are accurate and interchangeable for permeability estimation in closed loop perfusion method., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Objective: To determine the normal reference range for phenol red thread test (PRTT) values in clinically normal Syrian hamsters (Mesocricetus auratus)., Animals: Sixteen healthy adult Syrian hamsters (eight males and eight females) were used in this study., Procedure: Ophthalmic examinations were performed without chemical restraint. PRTT values were evaluated in both eyes of all Syrian hamsters using a commercial PRTT strip of a single lot number., Results: No statistically significant differences between right and left eyes were found for any of the results. The mean ± SD PRTT values for the study population were 6.8 ± 2.5 mm/15 s with a range from 3 to 11.5 mm/15 s. Mean PRTTs in male animals were 5.1 ± 1.2 mm/15 s, whereas mean PRTTs in female hamsters were 8.5 ± 2.3 mm/15 s. Comparison between mean PRTT values in males and females showed a significant difference (P = 0.004). Mean weights for males and females were 80.9 ± 4.8 and 90.6 ± 8.5 g, respectively. No linear relationship between mean PRTT and body weight was found in female (P = 0.46) and male (P = 0.92) hamsters., Conclusion: This study provides novel data for normal reference ranges of PRTT values in healthy Syrian hamsters. Results of this study may assist veterinarians in the diagnosis of ocular surface disease and syndromes affecting the tear film in these species., (© 2013 American College of Veterinary Ophthalmologists.)

An analytic study to validate a diagnostic test was carried out at the Institute of Gastroenterology in Havana, Cuba in adult patients of both sexes in whom chromoendoscopy was carried out with red phenol at 0.1% over the gastric mucosa for the detection of Helicobacter pylori infection between November 2008 and December 2010. The staining with red phenol at 0.1% is included in the invasive tests for the diagnosis of Helicobacter pylori infection and of the reactive techniques. The sensibility of red phenol dye in the diagnosis of Helicobacter pylori infection in the patients studied was of 72.6% with a confidence interval (C.I.) of 95% (64.9 to 79.2%) and a specificity of 75.5% C.I. 95% (61.9 to 85.4%). The positive predictive value was of 89.8% C.I. 95% (83.1 to 94.1%) and the negative predictive value of 48.1% C.I. 95% (37.3 to 59.0%). The proportion of false positives was of 24.5% C.I. 95% (14.6 to 38.1%)and the proportion of false negatives was of 27.4% C.I. 95% (20.8 to 35.1%). The diagnostic accuracy of the dye on the patients studied was 73.3% C.I. 95% (66.7 to 79.0%). The diagnostic odds ratio was 8.17 C.I. 95% (3.88 to 17.23), the J Youden ratio of 0.5 and the Kappa coefficient of 0.40 C.I. 95% (0.27 to 0.54). The staining dye with red phenol at 0.1% resulted in a useful method in the diagnosis of Helicobacter pylori infection in the gastric mucosa, it can be applied in our environment and has multiple advantages (topographic localization, avoids contamination and fast and immediate reading).

Purpose: To define a combination of the Schirmer I and phenol red thread (PRT) tests that improves the screening of patients with ocular sicca syndrome., Methods: The PRT test was performed before (PRT1) and after (PRT2) the Schirmer I test, in both eyes of 143 patients complaining of ocular dryness secondary to Sjögren's syndrome or sicca asthenia polyalgia syndrome (SAPS; 72 and 71 patients, respectively), and in 40 control patients. Groups were matched by age and sex. After determining the best cutoff values using the receiver operating characteristic procedure, several combinations of PRT and Schirmer I were assessed to improve the predictive values of the procedure., Results: The best cutoff value for PRT2, estimated at 15 mm, provided a satisfying match between sensitivity and specificity indexes (68% and 90%, respectively), similar to those obtained with the Schirmer I test. If PRT1 alone was ineffective to screen SGS from control patients, the comparison between PRT1 and PRT2 (so-called "DeltaPRT") was found as a good marker to detect patients with persistent tear reflex. Interestingly, the combination of positive Schirmer I, PRT 2, and/or ΔPRT tests was found to be highly predictive of severe ocular sicca syndrome., Conclusions: The combination of the Schirmer I and PRT tests strongly improves the screening procedure to detect patients with ocular dryness related to Sjögren's syndrome or SAPS. It could be more widely used in daily clinical practice, aside from the Schirmer I test, to optimize the work-up of patients presenting with dry-eye subjective signs.

Objective: To determine physiologic levels of tear production in Arabian (AH) and throughbred horses (TH) by using phenol red thread test (PRT)., Animals Studied: The study was performed on 16 AH and 14 TH, ranging from 2.5 to 24 years of age, housed in a stable situated in the Sanliurfa of Turkey., Procedures: For the measurement of PRT, the strip was placed under the lower eyelid approximately one-third the distance from the temporal to nasal canthus and left for 15 s. The length of the wet area was measured in mm and compared among breed, sex, and age groups and between eyes of both sides., Results: The mean length of the wet area was in AH and TH were 30.22 +/- 0.99 mm ranging from 16 to 41 and 31.00 +/- 1.4 mm ranging from 14 to 47, respectively. There were no significant differences in tear production among breed, sex, or age groups. The values measured for left eyes were significantly higher than those for right eyes (P < 0.05)., Conclusions: Phenol red thread test measurement is easily used, with no pain, and a comfortable method. PRT can be used in equine ophthalmology on a routine basis to the measurement of tear production. These normal PRT values help diagnosis keratoconjunctivitis sicca in horses.

Objective: To determine phenol red thread test (PRTT) values in eyes of clinically normal Hispaniolan Amazon parrots before and after topical application of an ophthalmic anesthetic agent and compare findings with Schirmer tear test (STT) values., Design: Evaluation study., Animals: 24 Amazona ventralis parrots from a research colony., Procedures: On 4 occasions (1-week intervals), all birds underwent a thorough ophthalmic examination of both eyes, which included (in sequence) performance of a PRTT and an STT; topical ocular application of proparacaine hydrochloride; and performance of another PRTT and another STT. Correlations between PRTT and STT values recorded with and without topical anesthesia were assessed., Results: Without topical anesthesia, mean +/- SD PRTT value was 12.5 +/- 5.0 mm/15 s (range, 1 to 25 mm/15 s). With topical anesthesia, the PRTT value was 12.6 +/- 5.4 mm/15 s (range, 2 to 24 mm/15 s). Without topical anesthesia, mean STT value was 7.9 +/- 2.6 mm/min (range, 0 to 13 mm/min). With topical anesthesia, the STT value was 5.1 +/- 3.3 mm/min (range, 0 to 18 mm/min). The correlation of PRTT and STT values recorded with or without topical anesthesia was weak (r = 0.51 and r = 0.32, respectively)., Conclusions and Clinical Relevance: Results indicated that the PRTT and STT were both viable methods for measurement of tear production in Hispaniolan Amazon parrots. Topical application of an ophthalmic anesthetic agent did not have a significant effect on the PRTT values but significantly decreased the STT values.

Background/aims: The (13)C-urea breath test (UBT) is a semiquantitative test for measuring Helicobacter pylori infection loading. H. pylori produces ammonia, which elevates the pH of the gastric mucosa and is detectable via endoscopy using a phenol red indicator. We evaluated whether this test could be used to diagnose H. pylori infection and whether phenol red staining was correlated with (13)C-UBT results., Methods: One hundred and twenty-three patients participated. The UBT was performed after ingestion of a capsule containing urea. A change in (13)C-UBT >2 ppt was selected as the cutoff value for diagnosing infection. After spraying evenly with a 0.1% phenol red solution, the pH of the gastric mucosal surface was measured using an antimony electrode through the biopsy channel., Results: The pH of stained mucosa (6.9+/-0.4) was significantly higher than that of unstained mucosa (1.9+/-0.8; p<0.001), and the H. pylori detection rate confirmed via histology was higher in stained versus unstained mucosa (p<0.01). Extensive mucosal staining resulted in a higher detection rate (p<0.001). The UBT produced results were very similar to those obtained via histological detection in stained mucosa (p<0.001). The extent of staining, expressed as a staining score, was positively correlated with the change in (13)C-UBT (r=0.426, p<0.001). A significant correlation was also observed between the histologically determined H. pylori density and (13)C-UBT results (r=0.674, p<0.001)., Conclusions: H. pylori infection elevates gastric mucosal surface pH, and endoscopic phenol red staining may be an alternative method for the diagnosis of H. pylori infection.

Object: To assess the results from using a commercially available phenol red thread (PRT) test with the eyes being kept open (as recommended by the company) vs a closed eye protocol (as used by some investigators)., Methods: A single PRT (Zone-Quick) test was carried out on 97 young adults (average age 21 years, range: 17-36) for 15 s with either the eyes open or closed. The right eye was assessed with 52 subjects undertaking the open eye test first, with the test being repeated 1 h later in the same indoor environment (temperature 21 degrees C and 40% humidity)., Results: The mean ( +/- S.D.) PRT value for the open eye protocol was marginally higher (at 20.5 +/- 7.0 mm) than for the closed eye (19.7 +/- 5.9 mm), but the overall outcome from the two protocols could range from being 18 mm greater in the open eye to 15 mm greater in the closed eye. Overall, the difference was not statistically different, neither were any substantial differences noted according to age, gender, iris colour, prior contact lens wear or according to which protocol was used first (p >or= 0.2)., Conclusion: These studies indicate that there can be a small difference in single PRT test data according to whether the eyes are kept open or closed, and it would be useful if the protocol used was clearly stated.

Aim: To measure the agreement between Schirmer's and phenol red thread tests in detecting dry eyes., Patients and Methods: A total of 103 patients attending preoperative cataract assessment clinic who agreed to be involved in the study were recruited. Each patient had one eye examined by both tests in a random order by two different investigators who were unaware of the results of the other test. Dry eye symptoms were assessed using an interviewer-administered questionnaire. The data were collected after the study period and analysed using kappa statistics to assess the agreement between the two tests., Results: Schirmer's test was positive in 25 patients when a cutoff point of 5 mm was used and positive in 41 patients with a cutoff point of 10 mm. Phenol red thread test was positive in four patients when a cutoff point of 10 mm was used and in 32 patients with a cutoff point of 20 mm. Kappa ranged from 0.067 to 0.3 indicating very weak agreement between the two tests. In all, 27% of the patients had symptoms of dry eyes; however, the agreement between each test and the symptoms was very poor., Conclusion: There is very weak agreement between Schirmer's test and phenol red thread tests and between each test and symptoms of dry eyes.

Objective: To develop a standard method for measuring tear production in large Psittaciformes using the phenol red thread (PRT) tear test. To establish mean PRT tear test values in clinically normal pet birds and to assess the reproducibility of the test., Animals: Two geographically distinct populations of healthy, large Psittaciformes (pilot study and study population). Species groups include: cockatoo (17), macaw (22), Amazon (10), African gray (1), eclectus (1) and pionus (1)., Procedure: The PRT was placed under the upper eyelid and both eyelids were held closed throughout the test. The PRT tear test was repeated after 2 months in the pilot study and after approximately 5 min in the study population., Results: The mean PRT tear test values for the pilot study were OD=28.2 mm/15 s (+/- 6.3 mm), OS=24.1 mm/15 s (+/- 6.6 mm) and OD=25.4 mm/15 s (+/- 3.3 mm), OS=25.5 mm/15 s (+/- 5.2 mm), for the first and second visits respectively. The mean PRT tear test value for the study population was: OD=19.8 mm/15 s (+/- 4.3 mm), OS=20.1 (+/- 3.9 mm) and OD=20.0 mm/15 s (+/- 4.5 mm), OS=19.1 mm/15 s (+/- 3.3 mm), for the first and second tests respectively. There was poor repeatability between tests., Conclusions and Clinical Relevance: Results suggest that the PRT tear test is a practical method for measuring tear production in large Psittaciformes, although adaptations to the established diagnostic method are necessary to overcome some anatomical differences present in birds. Good reproducibility of the PRT tear test could not be demonstrated in a clinically normal population of birds but geographic location appears to significantly influence results.

Purpose: To detect normal values of red phenol thread test in the Brazilian population and compare it between different races, age and sex., Methods: 280 white individuals (560 eyes) and 280 non-white individuals (560 eyes) were analyzed regarding sex and age, and analyzed using the Phenol Red test. Individuals with ocular diseases, contact lens or ocular drug users were excluded from this study., Results: Of the 1,120 evaluated eyes, the mean +/- standard deviation result was 19.77+/-7.90 mm., Conclusions: The mean result found in this study was an intermediate value compared to the previously studied populations (Japanese and American).

Purpose: Various measures are available to assess the tear film, yet little specific information is available on how they relate to each other. An exploratory study was undertaken to assess three measures and their relationship in non-contact lens wearers and in contact lens wearers., Methods: Forty-three young subjects (mean age, 25.0 +/- 3.1 years; 19 men and 24 women) without overt ocular disease were recruited and categorized into four similarly sized groups based on contact lens wear (no lens wear, conventional daily wear hydrogels, silicone hydrogel lenses worn on a continuous basis, and gas-permeable contact lenses). Sets of measures, in random order and from both eyes whenever possible, were made using a phenol red thread (PRT) test over 15 seconds (open eye), biomicroscopy to assess tear meniscus height (TMH) from a perpendicular perspective using a 0.05-mm resolution graticule, and a borosilicate glass micropipette used to collect a 5-microL sample of tears for assessment of osmolality by vapor pressure measures., Results: For the complete group of subjects, the TMH data averaged 0.22 +/- 0.07 mm; the average PRT wetting length was 18.0 +/- 6.1 mm; and the tear osmolality averaged 317 +/- 28 mOsm/kg. The intereye differences averaged 0.04 mm for TMH, 3.7 mm for PRT, and 15 mOsm/kg for tear osmolality. There were no detectable sex-related differences in the measures. Compared with the control group (average, 0.25 mm), the TMH data showed a trend to be lower in daily hydrogel (0.21 mm) and silicone hydrogel (0.20 mm) lens wearers, but not in gas-permeable lens wearers (0.24 mm). PRT data was bimodally distributed, with the control group showing slightly higher (average, 21.1 mm) wetting compared with hydrogel lens wearers (16.7 and 17.4 mm) and gas-permeable lens wearers (average, 17.3 mm). Hydrogel (319 mOsm/kg for both groups) and gas-permeable lens wearers (average, 324 mOsm/kg) had higher tear osmolality measures compared with the control group (average, 305 mOsm/kg). Although some of the differences approached statistical significance, any statistical differences were evident only after outliers were removed. However, on pooling all data, there was a statistically significant positive correlation between TMH and open-eye PRT measures (P < 0.001) and an indication of a negative correlation between open-eye PRT and tear osmolality measures., Conclusions: Even contemporary contact lens wear can have a small but measurable impact on the precorneal tear film osmolality or volume. The changes are internally consistent and, overall, support the idea that the PRT test provides a useful measure of tear meniscus volume.

Purpose: This study evaluated interexaminer agreement in the measurement of tear volume using the phenol red thread (PRT) test on Hong Kong-Chinese subjects. The effect of an intensive training session on interexaminer agreement was also investigated., Methods: Three postgraduate students without an optometry background were introduced to the use of the PRT test. After a general introduction (including a demonstration and some practice among themselves), the examiners collecting the first set of data from 38 subjects. They were then given an intensive 30-min training that involved strict standardization of instructions/procedures and practice. PRT values were collected from 27 subjects (four subjects participated in both phases of the study) after the intensive training., Results: Significant differences were found among the examiners before and after the intensive training, which was mainly due to examiner 1, who consistently obtained relatively lower mean PRT values in both testing sessions. The intraclass correlation values estimated for all examiners were 0.35 and 0.58 before and after the training session, respectively. The 95% limits of agreement after the training session ranged from -14.8 to 8.0 mm/15 s between examiners 1 and 3, who showed the largest difference, and from -8.8 to 9.3 mm/15 s between examiners 2 and 3, who showed the smallest difference. The latter pair also showed the most significant increase in agreement after the intensive training (intraclass correlation value increase from 0.29 to 0.65), although no significant differences in the PRT results were found between the two examiners before and after training., Conclusions: Our results suggest that the interexaminer agreement of PRT results is influenced by both examiner- and training-specific factors. Intensive training is important for ensuring the highest consistency among examiners. The moderate interexaminer agreement suggests that clinicians should seek a substantial difference in tear volume when making decisions regarding interventions for their Hong Kong-Chinese patients.

Objective: Systemic reactive AA amyloidosis is an intractable complication in patients with a long history of rheumatoid arthritis (RA). To help to more easily and reliably detect the presence of this form of amyloidosis in patients with RA and start intensive treatment as early as possible, we examined the sensitivity and usefulness of abdominal fat aspiration biopsy with phenol Congo red staining in the diagnosis of AA amyloidosis., Patients and Methods: Ten patients were diagnosed with systemic reactive AA amyloidosis secondary to RA (all women; mean age, 70.2 +/- 6.4 years; mean disease duration of RA, 20.3 +/- 11.2 years) based on histopathological examinations of biopsied specimens mainly from the gastroduodenal mucosa. Abdominal fat aspiration biopsy was performed in these patients, and the specimens were treated with both classical alkaline and phenol Congo red staining., Results: Phenol Congo red staining revealed amyloid deposits in all 10 patients, while conventional alkaline Congo red staining showed a positive result in 7 patients. In the patients with a positive result with alkaline Congo red staining, reactivity of one grade or two higher was demonstrated by the phenol Congo red method., Conclusion: Phenol Congo red staining is superior to the classical alkaline Congo red staining with respect to the detection of AA-amyloid deposits in biopsied abdominal fat tissue specimens. In addition to easy access and procedural safety, abdominal fat aspiration biopsy might contribute reliably to the diagnosis of systemic reactive AA amyloidosis secondary to RA when phenol Congo red staining is employed.

Background: Endoscopic spraying of phenol red dye and urea (phenol red test) has recently been used to assess the distribution of Helicobacter pylori in the gastric mucosa. We examined whether the phenol red test could be used to detect H. pylori in surgically resected stomachs., Methods: A total of 82 surgically resected stomachs, obtained from 82 patients (mean age, 60.1 years; range, 33-84 years) with early gastric carcinomas were examined. Phenol red solution and urea were sprayed over the entire mucosa of each resected stomach. A color change from yellow to red was considered as a positive reaction for H. pylori. Gastric mucosal specimens taken from positively stained and negatively stained areas on the phenol red test were then examined immunohistochemically to determine the degree of H. pylori colonization., Results: Diffusely positive reactions were seen in 16 resected stomachs (19%), and regionally positive reactions were seen in 36 (44%). The other 30 stomachs (37%) showed no color change (negative reaction). H. pylori was detected immunohistochemically significantly more frequently in positively stained than in negatively stained areas ( P << 0.0001). Specificity, sensitivity, and predictive values for positive and negative results of the phenol red test, determined on the basis of H. pylori immunostaining, were 100%, 74.3%, 100%, and 72.7%, respectively., Conclusions: The phenol red test is a specific, relatively sensitive, rapid, easy-to-use, and repeatable method that can be used to diagnose H. pylori infection in surgically resected material. It enables pathologists as well as gastroenterologists with no microbiological expertise to easily diagnose H. pylori infection.

Purpose: To determine the cut-off value of the phenol red-impregnated thread test (Zone-Quick((R)), Menicon trade mark ) for the diagnosis of ocular sicca syndrome using the ROC (receiver operating characteristic) procedure and to estimate the agreement with the Schirmer I test (without anesthetics)., Material: and methods: Fifty-four consecutive patients (including 50 females) with dry eyes, presumably related to an immune disorder, were recruited on the basis of subjective ocular symptoms and medical history (sicca syndrome). Both the phenol red thread (PRT) test and the Schirmer I test (testing periods, 15s and 5min, respectively) were performed in both eyes in random order. Only the lowest result for each test was used in statistical analyses. The same procedure was applied to 29 normal volunteers (no subjective symptoms). The patient and the control groups were matched for age and gender (mean age, 58.1 and 59.6, respectively)., Results: The ROC procedure showed that a cut-off value of 12mm in the PRT test provided the best ratio between sensitivity and specificity (56% and 69%, respectively) for the detection of dry eyes. Using this threshold, the agreement with the Schirmer I test was highly significant (kappa test; P<10(-3)). However, discordant results were observed in 32% of subjects., Conclusion: Giving a cut-off value at 12mm, the sensitivity and specificity of the PRT are 56% and 69%, respectively. Even if the agreement with the Schirmer I test is highly significant, 32% of patients have discordant results. These two methods of functional assessment of tear secretion are therefore complementary and further studies remain necessary to better understand the place of both tests in clinical practice.

Five methods of testing tears including the Schirmer tear test (STT-1), phenol red thread tear test (PRT) and modified Schirmer tear test (STT-2) were conducted on 44 eyes of 22 normal Beagles, and the tear film break up time (BUT) and lacrimal pH were tested in 32 eyes of 16 normal Beagles. The coefficient of variation of PRT demonstrated a low value (C.V. 12%) [corrected] compared to the value of STT-1 (C.V. 14%) [corrected]. The lacrimal pH showed a more constant value (C.V. 3%). Measurements of STT-2 (C.V. 48%) and BUT (C.V. 34%) varied significantly. The results show the clinical usefulness of the PRT. Mean values (mean +/- SD) of tests were: PRT, 29.3 +/- 3.45 mm/15 s; STT-1, 18.89 +/- 2.62 mm/60 s; STT-2, 9.52 +/- 4.55 mm/60 s; pH, 7.29 +/- 0.22 and BUT, 21.53 +/- 7.42 s.

Purpose: This study attempts to resolve whether the phenol red thread test (PRT) is a test of tear volume or tear production through comparisons with other techniques., Methods: Twenty asymptomatic subjects (10 men and 10 women; average age 30.6 +/- 10.8 years) had PRT (Zone Quick, Menicon) results compared with tear turnover rate (by fluorophotometry; Fluorotron Master, OcuMetrics) and tear volumes (from tear meniscus height and back extrapolation from fluorometric data)., Results: PRT wetting was not correlated with either tear turnover or volume (by fluorophotometry or tear meniscus height) on a Pearson product moment correlation test (p > 0.05)., Conclusions: No clear experimental evidence in favor of the PRT being a measure of tear production or volume was found. It is probable that the PRT measures uptake of a (small) amount of fluid residing in the eye, stimulates a low degree of reflex tearing, and reflects the absorption characteristics of the thread dependent on the biophysics or composition of tears.

Aim of Study: To determine whether a homemade rapid urease test (RUT) (1 mL of 10% urea broth in distilled water plus one drop of 1% phenol red as indicator, cost/test USD0.19) was reliable when compared to histology in the diagnosis of HP infection., Method: Prospective consecutive sampling of patients who underwent outpatient oesophagogastroduodenoscopy and antral biopsies from October 1996 to January 1997. RUT and histology examinations were done on all specimens. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the RUT were calculated accordingly., Results: Amongst our 140 patients, the sensitivity, specificity, positive and negative predictive values and accuracy of RUT were 94%, 99%, 99%, 95% and 96% respectively. Seventy-seven percent of the positive RUTs can be detected within 1 hour., Conclusion: Our homemade RUT is an inexpensive test with good sensitivity and specificity for HP infection.

To determine the clinical viability of a phenol red impregnated cotton thread in differentiating between normal, aqueous deficient and non-aqueous deficient dry eyes. Subjects were recruited on the basis of subjective symptoms, tear stability, rose bengal staining, Schirmer test, conjunctival hyperaemia, patency and number of meibomian glands, presence of mucin strands, appearance of lower tear meniscus. Based on the outcome of the tests, subjects were categorised as either aqueous deficient dry eyes, non-aqueous dry eyes or normals. Subjects were randomised and a thread was applied by inserting into the lower fornix of the right eye and leaving the thread in place for 120 sec. All data was collected under similar ambient conditions. After gathering all the data, the codes were broken. Mean (+/- S.D.) thread wetting values were, all dry eyes (n = 59) 18.4 mm (5.9). Aqueous deficient dry eyes (n = 35), 15.5 mm (4.6). Non-aqueous deficient dry eyes [n = 24], 22.7 mm (5.0). For the normals (n = 38), 19.4 mm (5.0). Differences between (i) normals and aqueous deficient dry eyes and (ii) aqueous deficient and non-aqueous deficient dry eyes were significant (p = 0.01). Difference between all dry eyes and normals was not significant. For the aqueous deficient and non-aqueous deficient dry eyes only, using a cut-off value of 20 mm the calculated sensitivity and specificity values were 86% and 83% respectively. This cotton thread test can effectively differentiate between aqueous deficient and non-aqueous deficient dry eye.

Objective: We developed an improved AFP kit for detecting AFP in leaked amniotic fluid. We studied the relationship between the results of the improved AFP kit and those of the intra-amniotic PSP dye-injection test (PSP test), and compared the results of two tests with the prognosis for subsequent pregnancy outcome, in order to know the diagnostic value of the two tests for preterm PROM, especially in equivocal cases., Methods: We compared the results of the AFP kit test with those of the PSP test in 8 equivocal cases of preterm PROM (18th to 34th weeks of gestation)., Results: The results of the AFP kit test coincided with those of the PSP test in all 8 equivocal cases of preterm PROM. The 4 cases that tested positive resulted in preterm deliveries; and the other 4 cases that tested negative resulted in full-term deliveries., Conclusion: The use of the AFP kit test is useful in assessing the prognosis for subsequent pregnancy in equivocal cases of preterm PROM. The rapid and accurate AFP kit test for diagnosing preterm PROM can be substituted for the PSP test in bedside and outpatient-clinic assessments.

A method for the laboratory production of a phenol red impregnated thread is described. Using the thread, tear flow was measured in the right eye of 2 groups of normal subjects: group I, n = 20, average age 26.2 years (+/- 5.6); and group II, n = 20, average age 56.4 years (+/- 13.8). Data were collected by placing a thread over the lower lid margin for a time period of 15 s. A further seven threads were inserted at 5 min intervals for periods increasing by 15 s up to 120 s. A significant difference in mean thread wetting between the two age groups was found for thread insertion times of 30, 60 and 90s. For each eye, the rate of thread wetting was exponentially related to the period of thread insertion. Thread wetting and the constant of the exponential were not found to be gender dependent. Simulating the tears in the lower fornix, using a bath of saline, it was concluded that the exponential constant was a property of thread material and not tear fluid. For practical purposes, the rate of thread wetting reached equilibrium by 120 s where mean total thread wetting was 19.5 mm (+/- 6.5). The typical flow of tears y in mm/s, along the phenol red thread can be described by: y = 0.16 + 0.47e-0.0283t where t is the period of thread insertion.

Two cases (27 and 23 weeks of gestation) diagnosed as high-leak PROM by an intra-amniotic dye (PSP) injection method later proved negative on re-testing by the same method, and ended in spontaneous reseal of the membranes. The pregnancies in these cases extended to 36 and 40 weeks of gestation without any eventful signs of infection.

Objective: In 1981, we preliminarily reported on the clinical value and safety of the intra-amniotic dye (Phenol-sulfonphthalein, PSP)-injection method for diagnosing PROM. In the current study, through examination of 64 equivocal cases in the midtrimester of pregnancy, we investigated the clinical efficacy of the PSP test., Methods: In the present study we examined patients with equivocal PROM in their 14th week to 33rd week of gestation, whose findings were positive according to a combination of conventional diagnostic methods. The results of the PSP test and conventional diagnostic methods were compared with the final diagnosis of PROM., Results: The conventional diagnostic methods showed an accuracy rate of 63.9%-70.5%, in contrast to the PSP test, which had a 100%-accuracy rate (p < 0.001)., Conclusion: Using the PSP test in combination with amnioscopy, we have established a method of differentially diagnosing PROM. We have reconfirmed the clinical efficacy of the PSP test in 64 equivocal PROM cases.

Purpose: To examine the results of the phenol red thread tear test in a cross-cultural comparison., Methods: Two groups of 500 controlled normal subjects who do not wear contact lenses from the United States and Japan were investigated., Results: The mean wet length of the thread for the United States was 23.9 mm (SD 9.5 mm). The mean for Japan was 18.8 mm (SD 8.6 mm). There was a significant difference between the two countries (P < 0.05). Males subjects had significantly longer wet lengths than females for both countries (P < 0.05). There was a moderate correlation between right and left eye results for both countries., Conclusions: The phenol red thread tear test was found to be easy to administer. Results were in line with current knowledge and theories of the lacrimal system. Results also indicated that this test may disclose subtle differences not previously found with other tear tests.

Helicobacter pylori (H. pylori) is known to show an uneven and patchy distribution on human gastric mucosa, close association with chronic gastritis and peptic ulcer diseases. The aim of this study was to clarify the distribution of this organism under direct vision by phenol red dye spraying endoscopy. In order to maintain gastric pH around pH 4.0 to 5.0, premedication was necessary either by intravenous injection of H2-blocker, 30 min before the test, or by oral administration of Omeprazole 20 mg or a half dose of H2-blocker before bedtime the day before the test. After that, 0.05% phenol red solution, containing 0.5 M urea, was sprayed onto the gastric mucosal via a teflon tube inserted through the endoscope. This technique was useful to clarify the distribution of H. pylori in the stomach in vivo and, it was possible to clinically study the role of H. pylori in upper G-I tract disorders, by this new technique.

The penicillin-phenol red acidometric test was found to be highly efficient and suitable for the detection of beta-lactamase production in staphylococci. The author presents his modification of the procedure and discusses its advantages. He recommends that all staphylococcal strains be tested for beta-lactamase production on the day of isolation.

The effect of inhaled ozone (O3) on the integrity of lung transport processes for phenol red has been determined. Phenol red (1, 10, or 100 mumol) was applied intratracheally to rat lungs in vivo and in an isolated lung preparation. In both test systems the rates of removal were found to be similar and to compare favorably with reported values. Animals exposed to O3 for 24 h demonstrated loss of carrier-mediated transport for this ion. The effect was also found to be related to the concentration of O3. These results indicate that the carrier-mediated component of phenol red removal from the airways of the lung may be used as a marker for pulmonary membrane damage resulting from the inhalation of atmospheric toxicants.

Phenol red has been shown to produce no effects on intestinal motility of 24-hour-old chickens, allowing for quantitative measures of gastrointestinal transit and emptying. The results show that 1 hr after ingestion, the main digestive contents are stored in the crop with lesser amounts in the muscular part of the stomach, in the ileum, and in the rectum and caeca.