The correlation between electrocardiographic parameters and mortality in non-cardiac ICU patients.

OBJECTIVE: This study aimed to determine the correlation between selected electrocardiogram (ECG) parameters (recorded at admission) and mortality in non-cardiac, non-COVID-19 intensive care unit (ICU) patients, and to determine the sensitivity and specificity of a novel admission ECG score (AD-ECG) for predicting mortality. Additionally, the sensitivity and specificity of the AD-ECG and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores for predicting ICU mortality were compared. PATIENTS AND METHODS: Clinical and laboratory data, and ECG parameters were compared between ICU survivors and non-survivors. ECG parameters (the QTc and Tpe intervals, and the Tpe/QT and Tpe/QTc ratios) and pulse pressure at ICU admission (baseline) were used to calculate the AD-ECG score. Cut-off values for ECG parameters, pulse pressure, and AD-ECG and APACHE II scores were calculated. The sensitivity and specificity of the APACHE II and AD-ECG scores were determined. RESULTS: The study included 167 patients. Mortality was higher in the patients with comorbidities, mechanical ventilation, and length of ICU stay (p < 0.05). The QTc and Tpe intervals, and the TPe/QT and TPe/QTc ratios differed significantly between the survivors and non-survivors (p < 0.05). The sensitivity and specificity of the AD-ECG score were similar to those of the APACHE II score. When pulse pressure, and the QTc and Tpe intervals were added to APACHE II, the sensitivity of the APACHE II score increased from 78.9% to 85.5%, and its specificity increased from 75% to 86.8%. CONCLUSIONS: A novel admission ECG score (AD-ECG) based on ECG parameters (the QTc and Tpe intervals, and the Tpe/QT and Tpe/QTc ratios) and pulse pressure has similar sensitivity and specificity as the APACHE II score for predicting non-cardiac ICU mortality. Adding pulse pressure, and the QTc and Tpe intervals increases the sensitivity and specificity of the APACHE II score; however, as the present study included non-cardiac patients only, additional larger-scale studies are needed to obtain more precise results.

Empagliflozin and sacubitril/valsartan reverse methotrexate cardiotoxicity by repressing oxidative stress and hypoxia in heart embryonic H9c2 cardiomyocytes - the role of morphology of mitochondria observed on electron microscopy.

OBJECTIVE: Oxidative stress and hypoxia play an important role in the pathogenesis of various cardiovascular diseases. We aimed to evaluate the effectiveness of sacubitril/valsartan (S/V) and Empagliflozin (EMPA) on hypoxia-inducible factor-1α (HIF-1α) and oxidative stress in H9c2 rat embryonic cardiomyocyte cells. MATERIALS AND METHODS: BH9c2 cardiomyocyte cells were treated with methotrexate (MTX) (10-0.156 µM), empagliflozin (EMPA; 10-0.153 µM) and sacubitril/valsartan (S/V; 100-1.062 µM) for 24, 48 and 72 h. The half maximum inhibitory concentration (IC50) and half maximum excitation concentration (EC50) values of MTX, EMPA and S/V were determined. The cells under investigation were exposed to 2.2 µM MTX before treatment with 2 µM EMPA and 25 µM S/V. The cell viability, lipid peroxidation, oxidation of proteins and antioxidant parameters were measured while morphological changes were also observed by transmission electron microscopy (TEM). RESULTS: The results showed that treatment with 2 µM EMPA, 25 µM S/V or their combination produced a protective effect against the reduction in cell viability caused by 2.2 µM MTX.  While HIF-1α levels plunged to their lowest with S/V treatment, oxidant parameters dipped, and antioxidant parameters soared to their highest level with S/V and EMPA combination treatment. A negative correlation was found between HIF-1α and total antioxidant capacity in the S/V treatment group. CONCLUSIONS: A significant decrease in HIF-1α and oxidant molecules together with an enhancement in antioxidant molecules and normalization of the mitochondria morphology as observed on electron microscopy in S/V and EMPA-treated cells were detected. Although S/V and EMPA have both protective effects against cardiac ischemia and oxidative damage, this effect may be increased more with S/V treatment alone compared to combined treatment.

Ranolazine exhibits anti-inflammatory and antioxidant activities in H9c2 cardiomyocytes.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of ranolazine on hypoxia-inducible factor-1α (HIF-1α) and oxidative stress in H9c2 cardiomyocyte cells. MATERIALS AND METHODS: We have assessed the effects of increasing concentrations of methotrexate (MTX) and ranolazine on proliferation of H9c2 rat cardiomyocyte cells by MTT assay. Malondialdehyde (MDA) protein oxidation [advanced oxidation protein products (AOPPs)], lipid hydroperoxide (LOOH) and xanthine oxidase (XO) activity as oxidative stress markers and HIF-1α levels increased and total thiol (T-SH), catalase (CAT) activity and total antioxidant capacity (TAC) antioxidant capacity markers decreased in MTX-treated cells compared to control cells. RESULTS: Oxidative stress markers decreased, and antioxidant capacity markers increased in cells treated with ranolazine alone compared to control cells. For all parameters, we showed that the levels of oxidant, antioxidant markers and HIF-1α in cells treated with MTX and ranolazine together reached the level of the control group, and ranolazine reversed the oxidative damage caused by MTX. CONCLUSIONS: The cell viability increased the levels of oxidant and prooxidant markers and decreased the levels of antioxidant markers decreased in H9c2 cardiomyocytes induced by oxidative stress. These results suggest that ranolazine may protect the cardiomyocytes from MTX-induced oxidative damage. The effects of ranolazine could result from its antioxidant properties.

The relationship of 50 bp deletion in the promoter region of SOD1 gene with viscosity and trace elements in chronic gastritis with Helicobacter Pylori: A case study.

The aim of research was to evaluate the superoxide dismutase-1 (SOD1) promoter region Insertion/Deletion (Ins/Del) gene variations in chronic gastritis patients infected with Helicobacter pylori (H. pylori), as well as the association between trace elements and viscosity. The study consisted 154 volunteer (18-65 age) with 107 H. pylori (+) and 47 (-). Biochemical parameters, whole blood viscosity (WBV), trace element levels and SOD1 promoter region Ins/Del gene variations were analyzed in blood samples provided from patients. It was determined that zinc (Zn), copper (Cu), iron (Fe) and magnesium (Mg) levels decreased whereas WBV, selenium (Se) and Cu/Zn ratio increased in H.pylori (+) chronic gastritis patients. The SOD1 50 bp Ins/Del gene polymorphism genotype and allele frequency distributions in H.pylori (+) and (-) chronic gastritis patients were not statistically significant. It was reported that Zn level decreased in H.pylori (+) patients with a deletion in at least one locus (Ins/Del+Del/Del), Se level increased. It has been found that the presence of H.pylori affects trace element metabolism and biochemical parameters in chronic gastritis patients. The 50 bp Ins/Del polymorphism in the promoter region of the SOD1 gene was shown to have no association with chronic gastritis. Investigation of different variants of the SOD1 gene in patients with gastritis will contribute to the determination of its role in the pathogenesis of the disease.

Zinc affects nuclear factor kappa b and DNA methyltransferase activity in C3H cancer fibroblast cells induced by a 2100 MHz electromagnetic field.

The use of mobile phones is becoming widespread with the development of technology, and as a result, its effects on human health are becoming more and more important every day. Studies have reported that the electromagnetic field (EMF) emitted by mobile phones may have adverse effects on the biological systems. In order to evaluate the effect of zinc (Zn) on C3H cancer fibroblast cells exposed to 2100 MHz EMF, we analyzed cell viability%, nuclear factor kappa b (NF-κB) and DNA methyltransferase (DNMT) activities. Cells were divided to following groups: Control, sham control, 2100 MHz EMF, 50 µM Zn + 2100 MHz EMF, 100 µM Zn + 2100 MHz EMF, and 200 µM Zn + 2100 MHz EMF for 2 h. We measurement cell viability, NF-κB and DNMT activities. There was increased cell viability % in the 2100 MHz EMF group compared to the control group, while the cell viability % was decreased in the 50, 100 and 200 µM Zn + 2100 MHz EMF groups compared to 2100 MHz EMF. NF-κB and DNMT activities were a significant increase in the 2100 MHz EMF group compared to the control group, although were statistically decreased in the 50, 100 and 200 µM Zn + 2100 MHz EMF groups compared to the 2100 MHz EMF group. Our results demonstrate that 2100 MHz EMF exposure in cancer fibroblast cells induce NF-κB and DNMT activities, whereas zinc supplementation reduce NF-κB and DNMT activities-induced 2100 MHz EMF.

The role of laparoscopic sleeve gastrectomy on inflammatory parameters in morbidly obese patients.

BACKGROUND: Obesity is an excessive increase in body fat mass and triggers chronic inflammation which causes increased fat accumulation in the visceral fat tissue. The aim of this study was to analyze serum zinc (Zn), Zn-alpha 2 glycoprotein (ZAG), peroxisome proliferator-activated receptor-γ (PPAR-γ) and nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) levels in morbidly obese patients before and after laparoscopic sleeve gastrectomy (LSG) and determine the association between alteration in body mass index (BMI), the % Excess Weight Loss (% EWL) and the biochemical parameters. METHODS: Thirty healthy individuals as a control group and 30 morbidly obese patients who had undergone LSG were enrolled in this study. Routine anthropometric and laboratory biochemical parameters in venous blood samples of groups at baseline and 1 and 12 months after LSG were recorded. RESULTS: Significant weight loss was achieved at 1 and 12 months after LSG. At baseline serum ZAG and PPAR-γ levels were lower, while NF-кB levels were higher in morbidly obese patients compared with the control group. Serum ZAG and PPAR-γ levels increased while NF-кB levels decreased 1 month and 12 months after LSG. Decreased %EWL was negatively correlated with changes in NF-кB, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), fasting plasma glucose and insulin at 12 months after LSG in morbidly obese patients. However, %EWL was positively correlated with changes in ZAG. CONCLUSIONS: Obesity was associated with down-regulated serum ZAG and PPAR-γ levels while up-regulated serum NF-кB. Our findings suggest that LSG ameliorates upregulating PPAR-γ expression, thereby inhibiting NF-κB-mediated inflammation by weight loss.

Response of TRPM2 Channel to Hypercapnic Acidosis and Role of Zn, Se, and GSH.

Hypercapnia can increase the production of reactive oxygen species (ROS) by inducing oxidative stress in cells. Transient receptor potential melastatin 2 (TRPM2) channel activation that is realized by ROS plays a critical role in the cellular mechanism. It was shown that antioxidants such as zinc (Zn), selenium (Se), and glutathione (GSH) can partake in the structures of enzymes and create a protective effect against oxidative stress. This study revealed the relationship between TRPM2 channel and hypercapnia, and the interaction of zinc, selenium, and glutathione. In our study, normoxia, hypercapnia, hypercapnia + Zn, hypercapnia + Se, and hypercapnia + GSH were created, in transfected HEK293 cells. The cells were exposed to normoxia or hypercapnia gasses in two different times (30 min and 60 min), while Zn, Se, and GSH were applied to the cells in the other groups before being exposed to the gas mixtures. The statistical evaluation showed a significant increase in lipid peroxidation (LPO) level and lactate dehydrogenase (LDH)% in the hypercapnia 30 min and 60 min groups, compared to the normoxia 30 min and 60 min groups, and an increase in LPO level and LDH% in the hypercapnia groups that Zn, Se, and GSH were applied. It was determined that in comparison with the normoxia 30 min and 60 min groups, the amount of inward Ca+2 current across TRPM2 channels and mean current density increased in the groups that were exposed to hypercapnia for 30 min and 60 min, while the same values significantly decreased in the hypercapnia groups that Zn, Se, and GSH were applied. Also, it was shown that oxidative stress rose as the duration of hypercapnia exposure increased. It was concluded that hypercapnia increased oxidative stress and caused cellular membrane damage, while the addition of Zn, Se, and GSH could protect the cell membrane from these damaging effects.

Association of TRPM5 Asn235Ser Polymorphism and Trace Elements/Minerals in Chronic Gastritis Patients: a Case-Control Study.

The link between chronic gastritis and chemosensory receptors is considered promising for disease prediction and treatment. The transient receptor potential melastatin member channel 5 (TRPM5) is an ion channel and may be a chemosensor in the gastrointestinal tract. Trace elements and minerals involved in many protein structures can change ion channel activity. Our study aimed to determine trace element and mineral levels according to TRPM5 Asn235Ser missense polymorphism distributions in patients with H. pylori (+) and (-) gastritis and to uncover their possible association with disease pathogenesis. In 109 volunteer patients diagnosed with gastritis [64 H. pylori (+), 45 H. pylori (-)], TRPM5 (Asn235Ser) polymorphism was detected by Kompetitive Allele-Specific PCR method (KASP), but no difference was found between the groups. There are differences between the serum trace element (Se, Zn, Cu, Mg, and Cu/Zn) levels of the two groups. High serum Se and Cu/Zn ratios were detected in H. pylori (+) patients. Cu/Zn ratio can be used as a marker of bacterial inflammation. The amount of Se was found to be statistically significant in the serums of H. pylori (+) patients carrying TT and CT genotype, while the amounts of Zn, Cu, and Mg were found as significant of H. pylori (-) patients. The relationship of Se with the H. pylori needs to be investigated further. In addition, H. pylori (+) patients have a significantly higher neutrophils/lymphocytes ratio (NLR) compared to those with H. pylori (-) NLR can be used as an indicator of inflammation.

The evaluation of prognostic value of acute phase reactants in the COVID-19.

AIMS: The aim of this study was to explain the demographic data, comorbidity and laboratory findings of our first cases in COVID-19 pneumonia in our country. METHODS: We gathered the data of COVID-19 pneumonia participants from our electronic medical system, including daily medical knowledge and laboratory, radiological, and microbiological results between March 10 to April 7, 2020. RESULTS: Totally, 125 patients, whose findings were compatible with COVID-19, were included in the study, 42 patients were excluded from the study. The distribution of genders was, 39 females (46.9 %), 44 males (53.01 %), the average age was 56.36 ± 16.25 (19-85). Hypertension above 60 years of age and diabetes mellitus under 60 years of age were the most common comorbidities. Neutrophils/ Lymphocyte percent(% NLR) was noted in 44 (53.01 %) patients, average: 3 (range 1.78-4.63). There was a statistically significant and positive relationship between D-dimer and C Reactive Protein (CRP) and ferritin. CONCLUSION: We detected that comorbidities, which were seen at COVID-19 disease differ according to the patients age. Besides that D-dimer, ferritin and CRP outcomes were particularly high and had a significant correlation with COVID-19 severity (Tab. 3, Fig. 2, Ref. 25). Text in PDF www.elis.sk Keywords: COVID-19, prognosis, acute phase reactan.

Allosteric modulation of α4ß2* nicotinic acetylcholine receptors: Desformylflustrabromine potentiates antiallodynic response of nicotine in a mouse model of neuropathic pain.

BACKGROUND: Neuronal nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels. The α4ß2 subtype of nAChRs plays an important role in the mediation of pain and several nicotine-evoked responses. Agonists and partial agonists of α4ß2 nAChRs show efficacy in animal pain models. In addition, the antinociceptive properties of nicotine, a non-selective nAChR agonist with a high affinity for α4ß2 nAChRs, is well-known. There is a growing body of evidence pointing to allosteric modulation of nAChRs as an alternative treatment strategy in experimental pain. Desformylflustrabromine (dFBr) is a positive allosteric modulator (PAM) at α4ß2 nAChRs that enhances agonist responses without activating receptors. We hypothesized that dFBr may enhance nicotine-induced antinociception. METHODS: The present study investigated whether dFBr could attenuate mouse chronic constriction injury (CCI)-induced neuropathic pain by increasing endogenous cholinergic tone or potentiating the nicotine-evoked antiallodynic response. RESULTS: We found that subcutaneous administration of dFBr failed to reduce pain behaviour on its own. However, the combination of dFBr with nicotine significantly reversed neuropathic pain behaviour dose- and time-dependently without motor impairment. Our data revealed that this effect was mediated by the α4ß2 nAChRs by using competitive α4ß2 antagonist dihydro-ß-erythroidine. In addition, dFBr failed to potentiate the antiallodynic effect of morphine, which shows the effect of dFBr is unique to α4ß2 nAChRs. CONCLUSIONS: The present results suggest that allosteric modulation of α4ß2 nAChR may provide new strategies in chronic neuropathic pain. SIGNIFICANCE: α4ß2 nAChRs are involved in pain modulation. dFBr, a PAM at α4ß2 nAChRs, potentiates the nicotine response dose-dependently in neuropathic pain. Thus, the present results suggest that allosteric modulation of α4ß2* nAChR may provide new strategies in chronic neuropathic pain.

A truly hybrid interventional MR/X-ray system: feasibility demonstration.

A system enabling both x-ray fluoroscopy and MRI in a single exam, without requiring patient repositioning, would be a powerful tool for image-guided interventions. We studied the technical issues related to acquisition of x-ray images inside an open MRI system (GE Signa SP). The system includes a flat-panel x-ray detector (GE Medical Systems) placed under the patient bed, a fixed-anode x-ray tube overhead with the anode-cathode axis aligned with the main magnetic field and a high-frequency x-ray generator (Lunar Corp.). New challenges investigated related to: 1) deflection and defocusing of the electron beam of the x-ray tube; 2) proper functioning of the flat panel; 3) effects on B0 field homogeneity; and 4) additional RF noise in the MR images. We have acquired high-quality x-ray and MR images without repositioning the object using our hybrid system, which demonstrates the feasibility of this new configuration. Further work is required to ensure that the highest possible image quality is achieved with both MR and x-ray modalities.

DQE(f) of four generations of computed radiography acquisition devices.

Measurements were made of the MTF(f), NPS(f), and DQE(f) of four generations of computed radiography (CR) imaging plates and three generations of CR image readers. The MTF generally showed only a minor change between generations of plates and readers, but the DQE(f) has improved substantially from a very early plate/reader combination to a more recent one. The DQE in the more recent plate/reader combination is 1.3X greater at low frequencies and about 3X greater at high frequencies than the much earlier versions. Thus there has been substantial improvement in the imaging performance obtainable with CR since some of the early observer studies which indicated poorer performance with CR than with screen-film.

A regional convolution kernel algorithm for scatter correction in dual-energy images: comparison to single-kernel algorithms.

Single kernel scatter correction algorithms are based on the model that the scatter field can be predicted by convolution of the primary intensity (Iprim) with a spatially invariant scatter point-spread function (PSF). Practical limitations (Iprim unknown) suggest the substitution of the total detected intensity (Idet) for Iprim as the source image in the convolution. In regions of high scatter fraction (SF), Idet is a poor approximation of Iprim, thereby causing an overestimation of scatter originating in the region. This contributes to errors in estimating detected scatter in the mediastinum and neighboring regions. A technique using a regionally variable point-spread function that significantly reduces RMS error in estimation of the primary image as compared to the single PSF method is investigated. The regionally variable convolution method employs a larger PSF in the mediastinum and a smaller PSF in the lungs to reduce the error in estimating the scatter throughout the image. The method to allow for patient differences has also been expanded and various implementations of these methods have been compared. Results show that the dual-kernel algorithm is always more effective than an equivalent single-kernel algorithm. The dual-kernel algorithm using a predicted scatter fraction curve gives an overall RMS error in the primary of as low as 20.8% which is equivalent to 8.7% RMS error in the scatter. The dual-kernel method using a predicted scatter fraction curve approaches the accuracy of the single-kernel method using patient specific scatter measurements. Because using individual scatter measurements is a less desirable method for clinical use, we feel that the dual-kernel algorithm which uses two regions specific convolution kernels and a variable scatter fraction curve is the preferable method.

Conventional chest radiography vs dual-energy computed radiography in the detection and characterization of pulmonary nodules.

OBJECTIVE: We evaluated a single-exposure, phosphor-plate, dual-energy imaging device that produces, in addition to conventional chest radiographs, both tissue- and bone-selective images. Our purpose was to determine whether dual-energy radiography was more accurate than routine chest radiography for detection and characterization of pulmonary nodules. SUBJECTS AND METHODS: Two hundred patients undergoing chest CT were asked to volunteer to have dual-energy and conventional chest radiographs obtained immediately before or after their CT scan. Radiographs from a subset of 50 of these patients with 116 CT-detected nodules and 10 patients with normal findings on CT scans of the chest were presented to the observers for the nodule detection study. Similarly, radiographs from a subset of 29 patients with 20 calcified and 20 uncalcified nodules were presented to five observers to determine nodule calcification. Dual-energy images were produced by filtering the X-ray tube output with a gadolinium sheet while using a multiple phosphor plate receptor. A dual-energy triad of images consisting of a conventional image, a tissue-selective image, and a bone-selective image were produced. The conventional chest radiographs and dual-energy image sets were presented to observers in random order. Data from a free response receiver operating curve and a receiver operating curve were generated for nodule detection and characterization, respectively. RESULTS: By using the dual-energy images, all five observers improved their ability to diagnose pulmonary nodules (p = .0005) and to characterize nodules as calcified (p = .005). CONCLUSION: By eliminating rib shadows with tissue-selective images and enhancing calcified structures with bone-selective images, dual-energy chest radiography improved the ability of all observers, regardless of expertise, to detect and characterize pulmonary nodules.

Single-exposure dual-energy computed radiography: improved detection and processing.

Recent reports have emphasized the potential for dual-energy computed radiographic applications. An improved method for single-exposure material-selective imaging with a photostimulable phosphor computed radiography system was investigated. The essential elements of the technique are (a) prefiltration with gadolinium, which divides the incident broad-beam x-ray spectrum into low-energy and high-energy peaks; (b) a cassette consisting of four photostimulable phosphor plates that record images of increasing mean energies, with a computed energy separation of 23 keV from the front to the rear plate; (c) spatially dependent scatter and beam-hardening corrections; and (d) a noise-reduction algorithm based on noise correlations between bone-selective and soft-tissue-selective dual-energy images. These elements result in improved material cancellation and signal-to-noise ratio throughout the image.

Digital subtraction angiography: principles and pitfalls of image improvement techniques.

The technology of imaging methods in digital subtraction angiography (DSA) is discussed in detail. Areas covered include function of the video camera in both interlaced and sequential scan modes, digitization by the analog-to-digital converter, logarithmic signal processing, dose rates, and acquisition of images using frame integration and pulsed-sequential techniques. Also discussed are various methods of improving image content and quality by both hardware and software modifications. These include the development of larger image intensifiers, larger matrices, video camera improvements, reregistration, hybrid subtraction, matched filtering, recursive filtering, DSA tomography, and edge enhancement.

Digital subtraction angiography: fundamental noise characteristics.

Detectability of low-contrast objects (vessels) in subtraction imaging depends on the noise properties of the image. There is a structure imposed upon the quantum noise that is due to the attenuation of the subtracted background object; this structure is referred to as a "noise print." It is shown to be a function of the manner of presubtraction processing (linear or logarithmic) and the local thickness of the attenuator in the x-ray beam path. The influence of the noise print on the visibility of vessels in subtraction images is demonstrated.

A technique of scatter and glare correction for videodensitometric studies in digital subtraction videoangiography.

The logarithmic amplification of video signals and the availability of data in digital form make digital subtraction videoangiography a suitable tool for videodensitometric estimation of physiological quantities. A system for this purpose was implemented with a digital video image processor. However, it was found that the radiation scattering and veiling glare present in the image-intensified video must be removed to make meaningful quantitations. An algorithm to make such a correction was developed and is presented. With this correction, the videodensitometry system was calibrated with phantoms and used to measure the left ventricular ejection fraction of a canine heart.

Digital video subtraction angiography for evaluation of peripheral vascular disease.

Digital video subtraction angiography (DVSA) has been employed to study a variety of peripheral vascular problems, using equipment developed at the University of Wisconsin. The technique is relatively simple and safe and has good patient acceptance. Experience indicates that in selected patients it is a satisfactory alternative to standard arteriography for screening and for definitive evaluation and on occasion may yield information not obtainable with conventional methods. It can aid in the performance of transluminal angioplasty and is suitable for serial evaluation of atherosclerotic vessels and bypass grafts.

Optimal x-ray spectra for screen-film mammography.

Theoretical and experimental techniques have been used to study optimal x-ray for screen-film mammography. A simple model of mammographic imaging predicts optimum x-ray energies which are significantly higher than the K-characteristic energies of Mo. A subjective comparison of x-ray spectra from Mo-anode and W-anode tubes indicates that spectra produced by a W-anode tube filtered with materials of atomic number just above that of Mo are more suitable for screen-film mammography than spectra produced by the Mo-anode/Mo-filter system. The imaging performance of K-edge filtered, W-anode tube spectra was compared to the performance of Mo-anode spectra using phantom measurements and mastectomy specimen radiography. It was shown that optimal W-anode spectra can produce equal contrast with an exposure reduction of a factor of two to three, a dose reduction of a factor of two, and equal or reducing tube loading, compared to Mo-anode spectra. A computer simulation was carried out to extend the initial, monoenergetic theory to the case of real, polychromatic sources. The effects of varying filter material and thickness, tube operating potential, and breast thickness were all studied. Since W-anode x-ray tubes are considered to be better for Xerox mammography than Mo-anode tubes, this study has shown that both Xerox and screen-film techniques can be performed optimally with a single, properly designed, W-anode x-ray tube.