Relative Increase In Sensitivity Research Articles

Towards core–shell engineering for efficient luminescence and temperature sensing

Research on the core–shell design of rare earth-doped nanoparticles has recently gained significant attention, particularly in exploring the synergistic effects of combining active and inert shell layers. In this study, we successfully synthesized 8 types of spherical core–shell Na-based nanoparticles to enhance the efficiency of core–shell design in upconversion luminescence and temperature sensing through the strategic arrangement of inert and active layers. The most effective upconversion luminescence was observed under 980 nm and 808 nm laser excitation using NaYF4 inert shell NaYF4:Yb3+, Er3+@ NaYF4 and NaYF4@ NaYF4:Yb3+, Nd3+ core–shell nanostructures. Moreover, the incorporation of the NaYbF4 active shell structure led to a significant increase in relative sensitivity in ratio luminescence thermometry. Notably, the NaYF4:Yb3+, Nd3+, Er3+@ NaYbF4 core–shell structure demonstrated the highest relative sensitivity of 1.12 %K−1. This research underscores the crucial role of inert shell layers in enhancing upconversion luminescence in core–shell structure design, while active layers play a key role in achieving high-sensitivity temperature detection capabilities.

Metal-free azo dyes anchored on CdS nanowires: Subtle solar cell exploration through experimental and DFT studies

Herein, as-synthesized azo dye (E)-2-isopropyl-5-methyl-4-((4-(4-nitrophenyl) thiazol-2-yl) diazenyl) phenol (D2) has been anchored on a high surface area one dimensional CdS nanowires (NWs) in thin film form. CdS nanowires have been grown through Cd(OH)2 template formation followed by conversion to CdS by ion-exchange route. The light-electricity conversion efficiency of the CdS-Azo dye-based solar cell has shown about 5-fold remarkable surge (0.159%) compared to the bare CdS (0.03%) with I3−/I− redox mediator under standard AM 1.5 illumination (100 mW cm−2). Albeit, the DFT studies revealed a higher band gap for pristine D2, alluringly it has depicted higher light-electricity conversion efficiency among the fabricated thin film solar cells after sensitization. The relative increase in sensitivity after sensitization is attributable to facile dye regeneration. Furthermore, after the co-sensitization of CdS thin film with equimolar cocktails of as-synthesized dyes and a natural dye Betanin (Bn), less efficiency was depicted ascribable to plausible dye aggregation upon blending.

Enhanced thermometry sensitivity in upconversion nanoparticles via near-field manipulation

Recently, nanoscale thermometry has attracted extensive attention. Here, we present an innovative approach to enhance the sensitivity of upconversion nanoparticles for thermometry through near-field manipulation. This method involves a composite structure consisting of photonic crystals and upconversion nanoparticles, with the near-field of the nanoparticles manipulated by tuning the absorption of the photonic crystals. The fluorescence intensity ratio (540nm/520 nm) of 4H11/2 and4S3/2 states of upconversion nanoparticles doped with Er3+ ions is sensitive to temperature change and employed as a temperature indicator that satisfies Boltzmann thermal equilibrium. The composite structure exhibited a relative thermometry sensitivity of 21.9 × 10−3 K−1 at 298 K, representing a significant improvement over pure core-shell upconversion nanoparticles with a 63.43% increase in relative sensitivity and a 675% increase in absolute sensitivity. This finding demonstrates the potential of our approach for advancing nanoscale thermometry.

How To Identify Familial Premature Myocardial Infarction: Comparing Approaches To Identify Familial Hypercholesterolemia

CONTEXT How best to identify families with premature myocardial infarction is unclear. OBJECTIVE We compared approaches to identify familial premature myocardial infarction in the general population using different familial hypercholesterolemia (FH) criteria and low-density lipoprotein (LDL) cholesterol cut-points. DESIGN AND SETTING Clinical and mutation criteria for FH and LDL cholesterol cut-points were applied for identification of familial premature myocardial infarction in 106,732 individuals from the Copenhagen General Population Study. RESULTS FH criteria identified 898 (13%) cases with familial premature myocardial infarction, leaving 5856 (87%) cases undetected. The ORs for familial premature myocardial infarction, compared with the respective remainder groups, were 4.7 (95% CI, 3.7 to 6.0) for clinical FH by Dutch Lipid Clinic Network criteria, 4.4 (4.0 to 4.7) for Simon Broome criteria, 2.1 (95% CI, 1.7 to 3.6) for Make Early Diagnosis to Prevent Early Death criteria, 2.1 (95% CI, 1.4 to 3.3) for FH mutation, and 1.4 (95% CI, 1.3 to1.6) for LDL cholesterol ≥5 mmol/L (193 mg/dL). For these risk groups, the sensitivity (true positive rate) for identification of familial premature myocardial infarction were 1.3%, 13%, 1.6%, 0.9%, and 7.1%, respectively. Compared with universal screening of a similar fraction of the population, the relative increase in sensitivity for these risk groups was 3.8-fold [fraction of population examined: 0.3%, 3.3-fold (4%), 2.0-fold (0.8%), 2.0-fold (0.4%), and 1.4-fold (5.3%), respectively]. CONCLUSION Criteria for FH identify a small fraction of individuals with familial premature myocardial infarction in the general population. Actively identifying families with premature myocardial infarction would be of potential preventive importance, and this study provides data that could be used to choose the best method for such family identification.

Interferon gamma release assays for Diagnostic Evaluation of Active tuberculosis (IDEA): test accuracy study and economic evaluation

Interferon gamma release assays (IGRAs) are blood tests recommended for the diagnosis of tuberculosis (TB) infection. There is currently uncertainty about the role and clinical utility of IGRAs in the diagnostic workup of suspected active TB in routine NHS clinical practice. To compare the diagnostic accuracy and cost-effectiveness of T-SPOT.TB ® (Oxford Immunotec, Abingdon, UK) and QuantiFERON® TB GOLD In-Tube (Cellestis, Carnegie, VIC, Australia) for diagnosis of suspected active TB and to estimate the diagnostic accuracy of second-generation IGRAs. Prospective within-patient comparative diagnostic accuracy study. Secondary care. Adults (aged ≥ 16 years) presenting as inpatients or outpatients at 12 NHS hospital trusts in London, Slough, Oxford, Leicester and Birmingham with suspected active TB. The index tests [T-SPOT.TB and QuantiFERON GOLD In-Tube (QFT-GIT)] and new enzyme-linked immunospot assays utilising novel Mycobacterium tuberculosis antigens (Rv3615c, Rv2654, Rv3879c and Rv3873) were verified against a composite reference standard applied by a panel of clinical experts blinded to IGRA results. Sensitivity, specificity, predictive values and likelihood ratios were calculated to determine diagnostic accuracy. A decision tree model was developed to calculate the incremental costs and incremental health utilities [quality-adjusted life-years (QALYs)] of changing from current practice to using an IGRA as an initial rule-out test. A total of 363 patients had active TB (culture-confirmed and highly probable TB cases), 439 had no active TB and 43 had an indeterminate final diagnosis. Comparing T-SPOT.TB and QFT-GIT, the sensitivities [95% confidence interval (CI)] were 82.3% (95% CI 77.7% to 85.9%) and 67.3% (95% CI 62.1% to 72.2%), respectively, whereas specificities were 82.6% (95% CI 78.6% to 86.1%) and 80.4% (95% CI 76.1% to 84.1%), respectively. T-SPOT.TB was more sensitive than QFT-GIT (relative sensitivity 1.22, 95% CI 1.14 to 1.31; p < 0.001), but the specificities were similar (relative specificity 1.02, 95% CI 0.97 to 1.08; p = 0.3). For both IGRAs the sensitivity was lower and the specificity was higher for human immunodeficiency virus (HIV)-positive than for HIV-negative patients. The most promising novel antigen was Rv3615c. The added value of Rv3615c to T-SPOT.TB was a 9% (95% CI 5% to 12%) relative increase in sensitivity at the expense of specificity, which had a relative decrease of 7% (95% CI 4% to 10%). The use of current IGRA tests for ruling out active TB is unlikely to be considered cost-effective if a QALY was valued at £20,000 or £30,000. For T-SPOT.TB, the probability of being cost-effective for a willingness to pay of £20,000/QALY was 26% and 21%, when patients with indeterminate test results were excluded or included, respectively. In comparison, the QFT-GIT probabilities were 8% and 6%. Although the use of IGRAs is cost saving, the health detriment is large owing to delay in diagnosing active TB, leading to prolonged illness. There was substantial between-patient variation in the tests used in the diagnostic pathway. The recruitment target for the HIV co-infected population was not achieved. Although T-SPOT.TB was more sensitive than QFT-GIT for the diagnosis of active TB, the tests are insufficiently sensitive for ruling out active TB in routine clinical practice in the UK. Novel assays offer some promise. The novel assays require evaluation in distinct clinical settings and in immunosuppressed patient groups. This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and the NIHR Health Protection Research Unit in Respiratory Infections, Imperial College London, London, UK.

CRISPR/Cas9-Mediated Trp53 and Brca2 Knockout to Generate Improved Murine Models of Ovarian High-Grade Serous Carcinoma.

There is a need for transplantable murine models of ovarian high-grade serous carcinoma (HGSC) with regard to mutations in the human disease to assist investigations of the relationships between tumor genotype, chemotherapy response, and immune microenvironment. In addressing this need, we performed whole-exome sequencing of ID8, the most widely used transplantable model of ovarian cancer, covering 194,000 exomes at a mean depth of 400× with 90% exons sequenced >50×. We found no functional mutations in genes characteristic of HGSC (Trp53, Brca1, Brca2, Nf1, and Rb1), and p53 remained transcriptionally active. Homologous recombination in ID8 remained intact in functional assays. Further, we found no mutations typical of clear cell carcinoma (Arid1a, Pik3ca), low-grade serous carcinoma (Braf), endometrioid (Ctnnb1), or mucinous (Kras) carcinomas. Using CRISPR/Cas9 gene editing, we modeled HGSC by generating novel ID8 derivatives that harbored single (Trp53-/-) or double (Trp53-/-;Brca2-/-) suppressor gene deletions. In these mutants, loss of p53 alone was sufficient to increase the growth rate of orthotopic tumors with significant effects observed on the immune microenvironment. Specifically, p53 loss increased expression of the myeloid attractant CCL2 and promoted the infiltration of immunosuppressive myeloid cell populations into primary tumors and their ascites. In Trp53-/-;Brca2-/- mutant cells, we documented a relative increase in sensitivity to the PARP inhibitor rucaparib and slower orthotopic tumor growth compared with Trp53-/- cells, with an appearance of intratumoral tertiary lymphoid structures rich in CD3+ T cells. This work validates new CRISPR-generated models of HGSC to investigate its biology and promote mechanism-based therapeutics discovery. Cancer Res; 76(20); 6118-29. ©2016 AACR.

Small-study effects and time trends in diagnostic test accuracy meta-analyses: a meta-epidemiological study.

BackgroundSmall-study effects and time trends have been identified in meta-analyses of randomized trials. We evaluated whether these effects are also present in meta-analyses of diagnostic test accuracy studies.MethodsA systematic search identified test accuracy meta-analyses published between May and September 2012. In each meta-analysis, the strength of the associations between estimated accuracy of the test (diagnostic odds ratio (DOR), sensitivity, and specificity) and sample size and between accuracy estimates and time since first publication were evaluated using meta-regression models. The regression coefficients over all meta-analyses were summarized using random effects meta-analysis.ResultsForty-six meta-analyses and their corresponding primary studies (N = 859) were included. There was a non-significant relative change in the DOR of 1.01 per 100 additional participants (95% CI 1.00 to 1.03; P = 0.07). In the subgroup of imaging studies, there was a relative increase in sensitivity of 1.13 per 100 additional diseased subjects (95% CI 1.05 to 1.22; P = 0.002). The relative change in DOR with time since first publication was 0.94 per 5 years (95% CI 0.80 to 1.10; P = 0.42). Sensitivity was lower in studies published later (relative change 0.89, 95% CI 0.80 to 0.99; P = 0.04).ConclusionsSmall-study effects and time trends do not seem to be as pronounced in meta-analyses of test accuracy studies as they are in meta-analyses of randomized trials. Small-study effects seem to be reversed in imaging, where larger studies tend to report higher sensitivity.Electronic supplementary materialThe online version of this article (doi:10.1186/s13643-015-0049-8) contains supplementary material, which is available to authorized users.

Numerical investigation of the two-dimensional gas temperature distribution based on tunable diode laser absorption spectroscopy

Based on tunable diode laser absorption spectroscopy and modified adaptive algebraic reconstruction technique, two-dimensional tomographic reconstruction was derived for the gas temperature distribution in the range of 600–1400 K in the controlled projections. It is explicitly shown that the quality of temperature reconstruction is heavily dependent on the relative sensitivity of the selected spectrum and the algorithm of modified adaptive algebraic reconstruction technique but independent of the complexity of the present field distribution. When the relative sensitivity is less than 1.5, the accuracy of reconstruction relates to the relative sensitivity of the selected spectrum and improves with the increase in relative sensitivity. When the relative sensitivity is larger than 1.5, the accuracy is mainly limited by the algorithm of modified adaptive algebraic reconstruction technique.

Local and Global Contrast Adaptation in Retinal Ganglion Cells

Retinal ganglion cells react to changes in visual contrast by adjusting their sensitivity and temporal filtering characteristics. This contrast adaptation has primarily been studied under spatially homogeneous stimulation. Yet, ganglion cell receptive fields are often characterized by spatial subfields, providing a substrate for nonlinear spatial processing. This raises the question whether contrast adaptation follows a similar subfield structure or whether it occurs globally over the receptive field even for local stimulation. We therefore recorded ganglion cell activity in isolated salamander retinas while locally changing visual contrast. Ganglion cells showed primarily global adaptation characteristics, with notable exceptions in certain aspects of temporal filtering. Surprisingly, some changes in filtering were most pronounced for locations where contrast did not change. This seemingly paradoxical effect can be explained by a simple computational model, which emphasizes the importance of local nonlinearities in the retina and suggests a reevaluation of previously reported local contrast adaptation.

Effects of age on thermal sensitivity in the rat.

Age-dependent changes in thermal sensitivity were evaluated with reflex- and operant-based assessment strategies in animals ranging in age from 8 to 32 months. The impact of inflammatory injury on thermal sensitivity was also determined in animals of different ages. The results showed that operant measures of escape behavior are needed to demonstrate significant changes in thermal sensitivity across the life span of female Long-Evans rats. Increased escape from both heat (44.5 degrees C) and cold (1.5 degrees C-15 degrees C) was observed for older animals, with a greater relative increase in sensitivity to cold. Physical performance deficits were demonstrated with aging but were not associated with changes in escape responding. Reflex responding to cold stimulation was impaired in older animals but was also influenced by physical disabilities. Reflex responding to heat was not affected by increasing age. Inflammation induced by formalin injections in the dorsal hindpaw increased thermal sensitivity significantly more in older animals than in their younger counterparts.

Abstract A21: Lung cancer surveillance with CT scan and autofluorescence bronchoscopy

Abstract Background: More than 75% of lung cancer patients are diagnosed at an advanced stage, when the survival rate is less than 15%. Sputum cytology, x-ray and CT scan have been evaluated as screening tools for early lung cancers, without much success. Auto-fluorescence bronchoscopy (AFB) has been recently shown to be effective in diagnosing central bronchial cancers. Combined surveillance with both spiral CT scan and AFB might help to increase the detection rate of the both central and peripheral lung cancers. Methods: The study included 205 patients who were enrolled in the High Risk Lung Cancer Surveillance Cohort at Roswell Park Cancer Institute (RPCI) with at least 2 of the following risk factors: (1) radiographically documented pulmonary asbestosis or; (2) a history of previously treated aero-digestive cancer or; (3) &amp;gt; 20 pack years smoking history or; (4) COPD with an FEV1 &amp;lt; 70% of predicted. Patients underwent spirometry testing, chest X-ray, sputum cytology, non-enhanced low dose spiral CT scan of the chest, and conventional white light/AF bronchoscopy with biopsy. Results: A total of 20 invasive cancers/CIS were diagnosed in the 205 patients. Seven were diagnosed at baseline, 4 within 1 year of enrollment and 9 on follow up of more than 1 year. Between them, AFB and CT scan diagnosed all baseline cancers. Only 3/7 cancers were detected on x-ray screening and only 1/7 patients demonstrated atypia on sputum cytology. Overall, 17 invasive cancers and 3 CIS were diagnosed during the surveillance study. All the 3 CIS were identified only on AFB. Of the 17 invasive cancers, CT scan detected 15 cancers (88%) and AFB detected 5 of these cancers (30%). CT scan showed a 67% relative increase in sensitivity for detecting prevalent cancers and 3 times greater sensitivity for incident and prevalent cancers compared to x-ray screening. CT scan and AFB detected 19 of the 20 CIS/cancers (95%), whereas x-ray and sputum cytology together detected only 5/20 CIS/cancers (25%). The sensitivity of CT scan and AFB in diagnosing pre-malignant lesions and cancers improved by almost two and half times relative to x-ray and sputum. Conclusion: The addition of AFB exam to yearly spiral CT scan of the chest could be a more efficient surveillance tool to identify early stage lung cancers, both in the central and peripheral lung. A greater efficiency and cost effectiveness can be achieved by limiting the use of the combination of AFB and CT scan in very high risk patients, selected based on their exposures and risk factors. Citation Information: Cancer Prev Res 2010;3(1 Suppl):A21.

An Additional Retinoid Binding Site in Rhodopsin

Recently we discovered that some dark-adapted salamander rods and cones generated an electrical response to the truncated retinal analogue, β-ionone. This finding was tempered by observations that exposure to β-ionone led to pigment bleaching, and that very high concentrations of β-ionone inhibited rod channels in patch experiments. Therefore we examined whether β-ionone could activate the visual pigments by attacking the chromophore-binding pocket or through an interaction at an alternate binding site. Microspectrophotometry showed an accumulation of β-ionone in green-sensitive rod outer segments that increased linearly with bath concentration indicating that β-ionone most likely partitioned into disk membranes. β-Ionone also went into blue-sensitive rod outer segments, however, uptake was higher than in green-sensitive rods at all bath concentrations tested, suggesting that β-ionone bound to at least one site on rhodopsin in addition to partitioning. X-ray diffraction of green-sensitive rod rhodopsin crystallized in the presence of millimolar concentrations of β-ionone revealed a binding site located near the extracellular/intradiskal side of rhodopsin. β-Ionone may have low efficacy and low binding affinity because rhodopsin with ligand bound retained the inactive state conformation. β-Ionone is not a native retinoid, so we also examined the effects of retinol. Dark-adapted green-sensitive rods exposed to retinol lost sensitivity to flashes due to direct rhodopsin activation. In addition, rods exhibited a relative increase in sensitivity to shorter wavelengths, consistent with the ability of retinol to act as an antenna chromophore. Similar effects were seen for a blue-sensitive rod. These results support the presence in opsins of a retinoid-binding site(s) in addition to the chromophore-binding pocket, and suggest that this alternate site(s) mediates a number of distinct ligand-specific effects.

Screening with a primary human papillomavirus test does not increase detection of cervical cancer and intraepithelial neoplasia 3

Aim: To determine cross-sectional validity of primary human papillomavirus (HPV) screening in comparison to cytological screening. Methods: During 2003–2004, 61,149 women were individually randomised to screening with a test for oncogenic HPV DNA or to conventional cytological screening within the Finnish cervical screening programme. Results: For HPV screening, cross-sectional relative sensitivity for cervical intraepithelial neoplasia (CIN) or cancer was 1.58 (95 % confidence interval 1.19–2.09) in comparison to cytology. At the level of CIN 3 or cancer no increase in relative sensitivity was observed. Cross-sectional specificity estimates for the screening arms were comparable, but the specificity of screening with sole HPV DNA test was clearly inferior. Conclusions: Primary HPV screening with cytology triage finds more CIN lesions compared to conventional screening but mild lesions are overrepresented. This is likely to result in overdiagnosis since most mild lesions are regressive.

Effect of an Asp905Tyr mutation of the glycogen-associated regulatory subunit of protein phosphatase-1 on the regulation of glycogen synthesis by insulin and cyclic adenosine 3',5'-monophosphate agonists.

The glycogen-associated regulatory subunit of protein phosphatase-1 (PP-1G) plays a major role in insulin-stimulated glycogen synthesis and thus the regulation of nonoxidative glucose disposal in skeletal muscle. In a general population of Caucasians a polymorphism at codon 905 of PP-1G from an aspartate to tyrosine has been reported to be associated with insulin resistance and hypersecretion. In this report functional studies were performed on rat skeletal muscle L6 cells stably transfected with an Asp905Tyr mutant PP-1G to evaluate the impact of this mutation on cellular responsiveness to insulin and cAMP. Although transfection resulted in a 3-fold increase in mutant PP-1G subunit expression, basal and insulin-stimulated PP-1 catalytic activities were decreased when compared with L6 cells transfected with wild-type PP-1G. The Asp905Tyr mutation resulted in an increase in cellular sensitivity to cAMP agonist, resulting in an inhibition of insulin's stimulatory effect on glycogen synthesis. More importantly, low concentrations of (Bu)2cAMP completely reversed insulin's stimulatory effects on glycogen synthesis when added to insulin-treated cells expressing mutant PP-1G. This was due to a rapid activation of glycogen phosphorylase a and a simultaneous inactivation of glycogen synthase via cAMP-mediated reductions in insulin-stimulated PP-1 catalytic activities. We conclude that an Asp905Tyr mutation of PP-1G is accompanied by a relative increase in sensitivity to cAMP agonists as well as a diminished capacity of the mutant PP-1G to effectively mediate the inhibitory effects of insulin on glycogen breakdown via PP-1 activation.

Trace analyses of arsenic in drinking water by inductively coupled plasma mass spectrometry: high resolution versus hydride generation.

A magnetic sector inductively coupled plasma mass spectrometer (ICPMS) was applied to the determination of arsenic in drinking water samples using standard liquid sample introduction in the high-resolution mode (M/delta M = 7800) and hydride generation in the low-resolution mode (M/delta M = 300). Although high mass resolution ICPMS allowed the spectral separation of the argon chloride interference, the accompanying reduction in sensitivity at high resolution compromised detection and determination limits to 0.3 and 0.7 microgram/L, respectively. Therefore, a hydride generation sample introduction method, utilizing a new membrane gas-liquid separator design, was developed to overcome the chloride interference. Due to the high transport efficiency and the 50-100 times higher sensitivity at M/delta M = 300, the HG-ICPMS method resulted in an over 2000-fold increase in relative sensitivity. The routine detection and quantification limits were 0.3 and 0.5 ng/L, respectively. The results for both methods applied to the analysis of over 400 drinking water samples showed very good agreement at concentrations above 1 microgram/L. For concentrations between 0.01 and 1 microgram/L, only HG-ICPMS provided accurate quantitative results. Membrane desolvation, mixed-gas plasmas, and the addition of organic solvents for the reduction of the ArCl+ interference were also investigated and evaluated for trace As determination.

Using flow cytometry to detect protozoa

For routine detection of Cryptosporidium and Giardia, flow cytometry with cell sorting bests IFA in terms of relative sensitivity as well as average cost, assay volume, assay time, and turnaround time.Flow cytometric cell sorting (FCCS), followed by microscopic verification, was evaluated as an alternative to immunofluorescence assay (IFA). Two hundred and sixty‐two water samples were stained with either indirectly conjugated or directly conjugated anti‐Cryptosporidium and anti‐Giardia antibodies and were examined by IFA and FCCS, respectively. Relative sensitivities of each assay were calculated by dividing the number of positive samples detected by one assay by the number of positive samples detected by either assay. When samples analyzed within five months of the initial IFA analysis were compared, the relative sensitivities of FCCS for detection of Cryptosporidium and Giardia were 94.1 and 78.6 percent, respectively, whereas the relative sensitivities using the IFA were 35.3 and 61.4 percent. Identification of Cryptosporidium and Giardia in water samples using FCCS takes less time, costs less, and analyzes a greater sample volume than the IFA. Given the nearly threefold increase in relative sensitivity for Cryptosporidium detection and the equal relative sensitivities for Giardia detection, the authors support the use of FCCS for routine detection of Cryptosporidium and Giardia in environmental samples.

Gender-Specific Criteria and Performance of the Exercise Electrocardiogram

Significant gender differences have been found in performance of the exercise ECG for the identification of coronary artery disease. However, identical exercise ECG ST segment criteria have been used in men and women, which might contribute to the lower accuracy of these methods in women than in men. To assess the effect of gender-specific test partitions on relative performance of standard and heart rate-adjusted ST segment depression criteria in men and women, the exercise ECGs of 143 women and 477 men were examined. Non-gender-specific test partitions, selected to have matched specificities of 96% for each test method, were determined in all 283 normal subjects, and gender-specific test partitions with identical specificity were determined separately in the 52 normal women and 231 normal men; sensitivity of these criteria was then examined in the 91 women and 246 men with coronary disease. Standard ST segment depression criteria (0.1 mV of additional horizontal or downsloping ST segment depression at end exercise) with identical 96% specificity in the entire group of normal subjects and separately in women and men had a significantly lower sensitivity of 51% in women compared with 67% in men (P < .01). Among women, performance of the ST segment/heart rate (ST/HR) slope was more improved than that of the ST/HR index by the use of gender-specific criteria. Compared with the performance of non-gender-specific criteria, application of gender-specific ST/HR slope partitions with matched specificity of 96% resulted in a significant increase in sensitivity in women from 84% to 91% (P < .01), with no significant change in sensitivity in men (89% to 88%) and with no residual difference in sensitivity between men and women. Although the use of gender-specific ST/HR slope criteria significantly improved sensitivity in both men and women with respect to standard criteria (each P < .0001), the relative increase in sensitivity provided by heart rate adjustment was significantly greater in women than in men (40% versus 21%, P < .001). Similar gender differences in improvement in performance using gender-specific criteria for the ST/HR slope were observed when analysis of test performance was restricted to the detection of three-vessel coronary disease (50% versus 9%, P = .002). At high specificity, gender-specific test partitions improve sensitivity of the ST/HR slope for the identification of coronary disease in women, with no decrease in sensitivity in men. In contrast, gender-specific partitions do not change performance of standard test criteria, which is lower in women than in men. Accordingly, the relative benefit of heart rate adjustment by the ST/HR slope method is greater in women than in men. These findings support use of the ST/HR slope with use of gender-specific partitions for the identification and quantification of coronary artery disease in both men and women.

Thymidine Phosphorylase Mediates the Sensitivity of Human Colon Carcinoma Cells to 5-Fluorouracil

Interferon-alpha (IFN alpha) potentiates the antitumor activity of 5-fluorouracil (FUra) in colon cancer in vitro, in vivo, and clinically. A likely mechanism for this action is the induction by IFN alpha of thymidine phosphorylase (TP), the first enzyme in one pathway for the metabolic activation of FUra to fluorodeoxyribonucleotides. To test this hypothesis, an expression vector containing the TP cDNA was transfected into HT-29 human colon carcinoma cells. Five stable transfectants were selected and analyzed. All showed increased sensitivity to FUra cytotoxicity, ranging from a 2-fold to a 19-fold decrease in the IC50 for FUra, compared to wild-type cells. Levels of TP mRNA, protein, and enzyme activity were elevated in the transfectants, and there was a significant correlation between the relative increase in sensitivity to FUra and both the increase in both TP mRNA levels and TP activity. Transfected cells exhibited increased formation of FdUMP, but not the ribonucleotides FUDP and FUTP, from FUra when compared to wild-type cells. The changes in TP activity, FdUMP formation, and FUra sensitivity in the transfected cells were comparable with those seen after treatment of wild-type cells with IFN alpha. These studies provide direct evidence for the role of TP in mediating the sensitivity of colon carcinoma cells to FUra, and further support the importance of the induction of TP in the biomodulating action of IFN alpha on FUra chemosensitivity.

Vascular Responsiveness in the Unstressed Borderline Hypertensive Rat

This study compares vascular responses of unstressed borderline hypertensive rats (BHR) to age-matched Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). Rings of thoracic aorta were mounted for isometric force determinations in tissue baths. Cumulative additions of phenylephrine (PE) or serotonin (5-HT) produced contractile responses in BHR aorta that were less than WKY but greater than SHR. Removing the endothelium increased force development to both agonists, with BHR showing the greatest increase. Based on EC50 determinations, no differences in PE sensitivity existed between groups, although in response to 5-HT, rings from SHR were significantly more sensitive than WKY. While the sensitivity of all rings increased with denuding, BHR showed a greater relative increase in sensitivity than WKY or SHR (intact EC50 divided by denuded EC50) to both PE and 5-HT. This suggests that there may be greater endothelium-derived relaxation in BHR than in WKY or SHR. In rings precontracted with 1 microM PE, the cumulative addition of acetylcholine resulted in greater relaxation in BHR than in SHR and WKY preparations. Thus, rings from unstressed BHR, which have only slightly higher blood pressures than WKY rats, demonstrate greater endothelium-mediated relaxation than WKY or SHR. Increased endothelium-derived relaxation may represent a possible mechanism for masking hypertension in BHR that is compromised as a result of exposure to a chronic stress paradigm.

Decreased Wound Neutrophils and Indiscrete Margination in the Pathogenesis of Wound Infection

To assess the pathogenesis of increased susceptibility to infection and septic death in a rat model, neutrophils (PMNs) in the wound, circulating PMNs, and their in vivo activity were evaluated after 30% and 60% burns. Eight hours after injury there were twice as many PMNs in the wounds of rats that sustained 30% compared with 60% burns. There was no difference between these two groups in the number of circulating PMNs at 2, 4, 6, and 8 hours after injury. In vivo evaluation of PMN response to infusion of F-Met-Leu-Phe revealed that circulating PMNs were more sensitive 4 hours after 60% burns compared with sham burns. At this time PMNs were found to be less sensitive to zymosan-activated serum infusion after 30% burns compared with sham burns. However, the PMNs in rats with 30% burns were more sensitive to this stimulus than were PMNs in rats with 60% injuries. Thus rats with greater injury, known to be more susceptible to wound infection, have fewer PMNs in their wounds 8 hours after injury. This is preceded by an increased sensitivity of PMNs in vivo to bacterial chemotactic factor and a relative increase in sensitivity to wound factors. This unusual finding implicates indiscrete margination as a factor in the pathogenesis of infection.