Efficacy of deep learning-based artificial intelligence models in screening and referring patients with diabetic retinopathy and glaucoma

Purpose

To analyze the efficacy of a deep learning (DL)-based artificial intelligence (AI)-based algorithm in detecting the presence of diabetic retinopathy (DR) and glaucoma suspect as compared to the diagnosis by specialists secondarily to explore whether the use of this algorithm can reduce the cross-referral in three clinical settings: a diabetologist clinic, retina clinic, and glaucoma clinic.

Methods

This is a prospective observational study. Patients between 35 and 65 years of age were recruited from glaucoma and retina clinics at a tertiary eye care hospital and a physician's clinic. Non-mydriatic fundus photography was performed according to the disease-specific protocols. These images were graded by the AI system and specialist graders and comparatively analyzed.

Results

Out of 1085 patients, 362 were seen at glaucoma clinics, 341 were seen at retina clinics, and 382 were seen at physician clinics. The kappa agreement between AI and the glaucoma grader was 85% [95% confidence interval (CI): 77.55-92.45%], and retina grading had 91.90% (95% CI: 87.78-96.02%). The retina grader from the glaucoma clinic had 85% agreement, and the glaucoma grader from the retina clinic had 73% agreement. The sensitivity and specificity of AI glaucoma grading were 79.37% (95% CI: 67.30-88.53%) and 99.45 (95% CI: 98.03-99.93), respectively; DR grading had 83.33% (95 CI: 51.59-97.91) and 98.86 (95% CI: 97.35-99.63). The cross-referral accuracy of DR and glaucoma was 89.57% and 95.43%, respectively.

Conclusion

DL-based AI systems showed high sensitivity and specificity in both patients with DR and glaucoma; also, there was a good agreement between the specialist graders and the AI system.

Association of OCT biomarkers and visual impairment in patients with diabetic macular oedema with vitreomacular adhesion

BACKGROUND

To analyse the distribution of spectral domain optical coherence tomography (SD-OCT) biomarkers in different types of vitreomacular adhesion (VMA) associated visual impairment in diabetic macular oedema.

METHODS

A total of 317 eyes of 202 patients were enrolled. Cases were divided into two groups focal VMA and broad VMA and subjects with no VMA were enrolled as controls. A grading platform was used for evaluating the morphology of diabetic macular oedema (DME), using good-quality SD-OCT images. Grading was done for VMA and the biomarkers. Best corrected visual acuity (BCVA), central retinal thickness (CRT) and central subfield thickness (CSFT) was also recorded.

RESULTS

The CRT (p = <0.001) and CSFT (p = <0.001) values were statistically significant between the groups. Except for Inner Nuclear Layer Cysts (p = <0.001), absence of Bridging Tissue that is composed of muller cell fibers and bipolar cells (p<0.001), and Hyper Reflective Dots (HRD) in cyst (p = 0.006) there were no significant differences in the distribution of OCT biomarkers among the 3 groups (focal VMA, broad VMA and no VMA). Only Disorganization of Retinal Inner Layers (DRIL) (p = 0.044) showed significant association with vision impairment in all the 3 groups.

CONCLUSION

The distribution of OCT biomarkers was similar across all eyes of cases and controls. However, they were more likely to be associated with visual impairment in the presence of VMA than no VMA.

Biological performance of metal metalloid (TiCuZrPd:B) TFMG fabricated by pulsed laser deposition

The aim of our study is to investigate the effect of boron with different ratios in Ti-Cu-Pd-Zr metallic glass (MG) matrix (Ti-Cu-Pd-Zr:B) fabricated by Pulsed Laser Deposition (PLD) for biomedical implants. The Ti based Thin Film Metallic Glasses (TFMGs) in combination with boron (in different atomic %) was assessed in attaining the combined properties, like outstanding corrosion resistant properties and good biocompatibility in this work. The disordered structure and amorphous nature of the Ti-Cu-Pd-Zr:B thin films systems were achieved by the PLD process and affirmed by XRD and transmission electron microscopy. The boron incorporation in the TFMG has been elucidated by XPS analysis. The boron containing films displays distribution of boron protuberances interleaved in the amorphous matrix was stated from SEM analysis. It is found that increase in atomic percentage of boron contents in TFMG results in the improvement in glass transition temperatures. The electrochemical parameters suggest better corrosion resistance and capabilities of passivity when boron percentage was increased in the film thereby preventing adverse biological reactions. TFMGs exhibited excellent hemocompatibility by preventing the platelet activation. MTT assay manifests increase in cell concentration with culture period on the TFMGs for the MC3T3-E1 preosteoblasts cells. Cell morphology was also studied which confirmed the viable state of the cells on the TFMG surfaces. The combination of such distinctive properties marks these TFMG systems as prospective aspirants for biomedical implants.

Respiratory health status is associated with treatment outcomes in pulmonary tuberculosis

<sec id="st1"> <title>BACKGROUND</title> The association between respiratory impairment and tuberculosis (TB) treatment outcomes is not clear. </sec> <sec id="st2"> <title>METHODS</title> We prospectively evaluated respiratory health status, measured using the Saint George's Respiratory Questionnaire (SGRQ), in a cohort of new adult pulmonary TB cases during and up to 18 months following treatment in India. Associations between total SGRQ scores and poor treatment outcomes of failure, recurrence and all-cause death were measured using multivariable Poisson regression. </sec> <sec id="st3"> <title>RESULTS</title> We enrolled 455 participants contributing 619 person-years at risk; 39 failed treatment, 23 had recurrence and 16 died. The median age was 38 years (interquartile range 26-49); 147 (32%) ever smoked. SGRQ scores at treatment initiation were predictive of death during treatment (14% higher risk per 4-point increase in baseline SGRQ scores, 95%CI 2-28, P = 0.01). Improvement in SGRQ scores during treatment was associated with a lower risk of failure (1% lower risk for every per cent improvement during treatment, 95%CI 1-2, P = 0.05). Clinically relevant worsening in SGRQ scores following successful treatment was associated with a higher risk of recurrence (15% higher risk per 4-point increase scores, 95%CI 4-27, P = 0.004). </sec> <sec id="st4"> <title>CONCLUSION</title> Impaired respiratory health status was associated with poor TB treatment outcomes. The SGRQ may be used to monitor treatment response and predict the risk of death in pulmonary TB. </sec>.

Cytocompatibility assessment of Ti-Nb-Zr-Si thin film metallic glasses with enhanced osteoblast differentiation for biomedical applications

Biologically safe Ti-based quaternary Ti-Nb-Zr-Si thin film metallic glass (TFMG) was fabricated by sputtering on Titanium alloy (Ti6Al4V or Ti alloy) substrates. A preliminary assessment regarding glass forming ability, thermal stability and corrosion behavior was performed. The amorphous nature of the film is evidenced from the X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM) and Selected Area Electron Diffraction (SAED) patterns. Ion scattering spectroscopy (ISS) and X-ray Photoelectron Spectroscopy (XPS) were used to analyse the chemical composition of surface which indicated oxygen on the top surface of the film and confirms the presence of Ti, Nb, Si, Zr without any other impurities. The surface morphology of the film showed a smooth surface as observed from scanning electron microscope (SEM) and atomic force microscope (AFM) analysis. It is found that the TFMG can sustain in the body-fluid, exhibiting superior corrosion resistance and electrochemical stability than the bare titanium. The cytotoxicity studies with L929 fibroblast cells showed that coatings were graded as zero and non-cytotoxic in nature. No hemolysis was observed on the coated surface indicating a better hemocompatibility. Assay using SaOS-2 bone cells showed good growth on the coated surfaces. The calcium assay showed that the SaOS-2 cells grown and differentiated on the control (Tissue Culture Polystyrene) TCPS surface had the highest mineral level. Higher alkaline phosphatase activity is obtained in SaOS-2 osteoblast cell cultures on TFMG than the control.

Effect of Ablation Rate on the Microstructure and Electrochromic Properties of Pulsed-Laser-Deposited Molybdenum Oxide Thin Films

Molybdenum trioxide (MoO₃) is a well-known electrochromic material. In the present work, n-type α-MoO₃ thin films with both direct and indirect band gaps were fabricated by varying the laser repetition (ablation) rate in a pulsed laser deposition (PLD) system at a constant reactive O₂ pressure. The electrochromic properties of the films are compared and correlated to the microstructure and molecular-level coordination. Mixed amorphous and textured crystallites evolve at the microstructural level. At the molecular level, using NMR and EPR, we show that the change in the repetition rate results in a variation of the molybdenum coordination with oxygen: at low repetition rates (2 Hz), the larger the octahedral coordination, and greater the texture, whereas at 10 Hz, tetrahedral coordination is significant. The anion vacancies also introduce a large density of defect states into the band gap, as evidenced by XPS studies of the valence band and supported by DFT calculations. The electrochromic contrast improved remarkably by almost 100% at higher repetition rates whereas the switching speed decreased by almost 6-fold. Although the electrochromic contrast and coloration efficiency were better at higher repetition rates, the switching speed, reversibility, and stability were better at low repetition rates. This difference in the electrochromic properties of the two MoO₃ films is attributed to the variation in the defect and molecular coordination states of the Mo cation.

Chromatographic, NMR and vibrational spectroscopic investigations of astaxanthin esters: application to "Astaxanthin-rich shrimp oil" obtained from processing of Nordic shrimps

Astaxanthin (ASTX) is a keto carotenoid, which possesses a non-polar linear central conjugated chain and polar β-ionone rings with ketone and hydroxyl groups at the extreme ends. It is well known as a super anti-oxidant, and recent clinical studies have established its nutritional benefits. Although it occurs in several forms, including free molecule, crystalline, aggregates and various geometrical isomers, in nature it exists primarily in the form of esters. Marine animals accumulate ASTX from primary sources such as algae. Nordic shrimps (P. borealis), which are harvested widely in the Atlantic Ocean, form a major source of astaxanthin esters. "Astaxanthin-rich shrimp oil" was developed as a novel product in a shrimp processing plant in Eastern Canada. A compositional analysis of the shrimp oil was performed, with a view to possibly use it as a nutraceutical product for humans and animals. Astaxanthin-rich shrimp oil contains 50% MUFAs and 22% PUFAs, of which 20% are omega-3. In addition, the shrimp oil contains interesting amounts of EPA and DHA, with 10%/w and 8%/w, respectively. Astaxanthin concentrations varied between 400 and 1000 ppm, depending on the harvesting season of the shrimp. Astaxanthin and its esters were isolated from the oil and analysed by NMR, FTIR and Micro-Raman spectroscopy. Astaxanthin mono- and diesters were synthesized and used as standards for the analysis of astaxanthin-rich shrimp oil. NMR and vibrational spectroscopy techniques were successfully used for the rapid characterization of monoesters and diesters of astaxanthin. Raman spectroscopy provided important intermolecular interactions present in the esterified forms of astaxanthin molecules. Also discussed in this paper is the use of NMR, FTIR and Micro-Raman spectroscopy for the detection of astaxanthin esters in shrimp oil.

Enhancement of bioactivity of titanium carbonitride nanocomposite thin films on steels with biosynthesized hydroxyapatite

Thin films of titanium carbonitride (TiCN) were fabricated by DC magnetron sputtering on medical grade steel. The biocompatibility of the coating was further enhanced by growing hydroxyapatite crystals over the TiCN-coated substrates using biologically activated ammonia from synthetic urine. The coatings were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy (SEM)-energy dispersive spectroscopy, and Raman spectroscopy. The electrochemical behavior of the coatings was determined in simulated body fluid. In addition, hemocompatibility was assessed by monitoring the attachment of platelets on the coating using SEM. The wettability of the coatings was measured in order to correlate with biocompatibility results. Formation of a coating with granular morphology and the preferred orientation was confirmed by SEM and X-ray diffraction results. The hydroxyapatite coating led to a decrease in thrombogenicity, resulting in controlled blood clot formation, hence demonstrating the hemocompatibility of the coating.

Nanocrystallization in magnetron sputtered Zr–Cu–Al–Ag thin film metallic glasses

Zr-based thin film metallic glasses (TFMG) were fabricated from a polycrystalline Zr₄₈Cu₃₆Al₈Ag₈ (at.%) target by DC magnetron sputtering. A series of characterization techniques were employed to study the structure, composition and thermal stability of the glassy coating. Annealing studies show nanocrystallites of CuZr₂ in an amorphous matrix.

Enhancement of biocompatibility of metal implants by nanoscale tiN/NbN multilayer coatings

Titanium nitride (TiN)/niobium nitride (NbN) nanostructured multilayer coatings were prepared by DC reactive magnetron sputtering method using the combination of a titanium and niobium target and an Ar-N2 mixture discharge gas on to 316L stainless steel substrates. The coatings showed a polycrystalline structure with (111) for TiN and (101) for NbN preferential growth. Raman spectroscopy measurements on the multilayer films exhibited the characteristic peaks at 212, 303, 458 and 578 cm-1. A higher hardness of 38 GPa was observed for TiN/NbN coatings. Electrochemical polarization tests were performed in simulated biological fluid solutions at 37 degreesC in order to determine and compare the corrosion behavior of the coated and uncoated 316L SS substrates. The TiN/NbN multilayer coatings could improve the corrosion resistance of 316L SS substrate. The bacterial culture experiments were performed and the bacteria treated samples were examined by epi fluorescence microscope measurements.

Surface modification of 316L stainless steel with magnetron sputtered TiN/VN nanoscale multilayers for bio implant applications

Nanoscale multilayered TiN/VN coatings were developed by reactive dc magnetron sputtering on 316L stainless steel substrates. The coatings showed a polycrystalline cubic structure with (111) preferential growth. XPS analysis indicated the presence of peaks corresponding to Ti2p, V2p, N1s, O1s, and C1s. Raman spectra exhibited the characteristic peaks in the acoustic range of 160-320 cm(-1) and in the optic range between 480 and 695 cm(-1). Columnar structure of the coatings was observed from TEM analysis. The number of adherent platelets on the surface of the TiN/VN multilayer, VN, TiN single layer coating exhibit fewer aggregation and pseudopodium than on substrates. The wear resistance of the multilayer coatings increases obviously as a result of their high hardness. Tafel plots in simulated bodily fluid showed lower corrosion rate for the TiN/VN nanoscale multilayer coatings compared to single layer and bare 316L SS substrate.

Psychopathology, traumatic life events, and coping skills among patients attending a primary-care adolescent clinic

OBJECTIVE

To compare the type of life events experienced and coping styles used by adolescents with and without psychopathology, attending a primary-care adolescent clinic.

METHODS

One hundred adolescents with and without psychopathology attending a drop-in adolescent clinic in a tertiary-care teaching hospital were recruited. Face-to-face interview used Child Behaviour Checklist, Life Event Scale, Coddington's life event scale, Impact of Event Scale and Modified Jalowiec coping scale as measures after getting written, informed consent from the primary care-giver and verbal assent from the adolescents. Bivariate and multivariate comparisons were done between the groups appropriately.

RESULTS

Adolescents with psychopathology had experienced more parental fights, increased arguments with parents, increased arguments between parents, serious illness requiring hospitalization of the adolescent. The intrusive symptoms of PTSD were noted more than avoidant symptoms among those adolescents with life events. Confrontative, emotive and optimistic coping styles were most often used in adolescent with psychopathology.

CONCLUSIONS

In India, adolescents with psychopathology attending a primary care clinic have significant life events and different coping styles. Therefore, adolescents with psychopathology in this setting should be screened for life events as well as dysfunctional coping styles and given appropriate intervention.

Regeneration of three-way automobile catalysts using biodegradable metal chelating agent--S, S-ethylenediamine disuccinic acid (S, S-EDDS)

Regeneration of the activity of three-way catalytic converters (TWCs) was tested for the first time using a biodegradable metal chelating agent (S, S-ethylenediamine disuccinic acid (S, S-EDDS). The efficiency of this novel environmentally friendly solvent in removing various contaminants such as P, Zn, Pb, Cu and S from commercial aged three-way catalysts, and improving their catalytic performance towards CO and NO pollutants removal has been investigated. Four samples of catalysts from the front and rear inlets of two different TWCs with different mileages and aged under completely different driving conditions were investigated. The catalysts were characterized using various techniques, such as X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area measurements (N(2) adsorption at 77 K). Quantitative ICP-MS analyses and SEM-EDS studies show the removal of Zn, P and Pb. SEM-EDS images obtained at low magnification (50 μm) showed considerable differences in the surface morphology and composition after washing with S, S-EDDS. However, XRD studies indicated neither little to no removal of major contaminant compound phases nor major structural changes due to washing. Correspondingly, little or no enhancement in BET surface area was observed between the used and washed samples. Light-off curves show that the regeneration procedure employed can effectively improve the catalytic performance towards NO pollutant.

Eimeria maxima recombinant Gam82 gametocyte antigen vaccine protects against coccidiosis and augments humoral and cell-mediated immunity (46.19)

Intestinal infection with Eimeria, the etiologic agent of avian coccidiosis, stimulates protective immunity to subsequent colonization by the homologous parasite, whilst cross-protection against heterologous species is poor. This study was designed to assess a purified recombinant protein from E. maxima gametocytes (Gam82) in stimulating immunity against experimental infection with live parasites. Following Gam82 intramuscular immunization and oral parasite challenge, body weight gain, fecal oocyst output, gut lesions, serum antibody response, cytokine production, and lymphoproliferation were assessed to evaluate vaccination efficacy. Animals vaccinated with Gam82 and challenged with E. maxima showed lower oocyst shedding and reduced intestinal pathology compared with non-vaccinated and parasite-challenged animals. Gam82 vaccination also stimulated the production of antigen-specific serum antibodies, induced greater levels of IL-2 and IL-15 mRNAs, and increased splenic lymphoproliferation compared with non-vaccinated controls. These results demonstrate that the Gam82 recombinant protein protects against coccidiosis and augments humoral and cell-mediated immunity.

An experimental study on using a diagnostic computed radiography system as a quality assurance tool in radiotherapy

The advent of improved digital imaging modalities in diagnostic and therapy is fast making conventional films a nonexistent entity. However, several radiotherapy centers still persist with film for performing quality assurance (QA) tests. This paper investigates the feasibility of using a diagnostic computed radiography (CR) system as a QA tool in radiotherapy. QA tests such as light field congruence, field size verification, determination of radiation isocentre size, multileaf collimator (MLC) check and determination of isocentric shift for stereotactic radiosurgery (SRS) were performed and compared with film. The maximum variation observed between CR and film was 0.4 mm for field size verification, -0.13 mm for the radiation isocentre size check, 0.77 for MLC check and -0.1 mm for isocentric shift using the Winston Lutz test tool for SRS QA. From these results obtained with the CR it is concluded that a diagnostic CR system can be an excellent cost-effective digital alternative to therapy film as a tool for QA in radiotherapy.

Cysticercosis of the oral cavity: an often misdiagnosed entity

We present a case report of a single lesion of cysticercosis cellulosae, a parasitic infection caused by the larval stage of Taenia solium (pork tapeworm), presenting as a soft tissue swelling of the lower lip. We stress the importance of knowledge about oral manifestations of parasitic infections.

Influence of Adyar river in the coastal waters of Chennai (Madras), Bay of Bengal

The impact of the river Adyar which is influenced by industrial wastes and domestic sewage from the city of Chennai (Madras), on the hydrobiology of coastal water in the Bay of Bengal was evaluated. Reduction in pH, dissolved oxygen (DO), nitrite, nitrate, primary productivity and increase of ammonia, phosphate, silicate, heavy metals, biological oxygen demand (BOD), chlorophyll pigments, particulate organic carbon (POC), respiration, suspended solids, ATP, and bacteria in the mixing site during low tide indicated that the Adyar water was heavily polluted and ultimately affect the quality of coastal water near the vicinity of mixing zone. The effects are diluted or nullified as the distance increased from the mixing site due to heavy mixing and littoral current. During high tide, the flow was completely stopped and little or no effect was recorded. The light, water current and wave action are the important factors which minimize the pollution impacts in the receiving coastal water.

Progression of heterogeneous breast tumors

Two possible pathways of breast tumor progression were investigated by searching for values of transition rates that could reproduce the clinically observed co-occurrence frequencies of grades of ductal carcinoma in situ and grades of invasive ductal carcinoma in heterogeneous tumors. Two different pathways were analysed, a linear pathway with seven parameters, and a nonlinear pathway with three parameters. In each pathway ductal carcinoma in situ (DCIS) is a progenitor of invasive carcinoma (IDC). In the linear pathway breast tumor progression is along increasing grades: DCIS 1-DCIS 2-DCIS 3-IDC 1-IDC 2-IDC 3. In the nonlinear pathway progression of DCIS and progression of IDC can proceed in parallel steps, and in addition, with transitions from each grade of DCIS to a corresponding grade of IDC. The biological pathways were interpreted mathematically as compartment models with transition rates between stages in an explicit series of coupled differential equations. Two methods were used to search for transition rates that could reproduce the observed co-occurrence frequencies, a limited empirical search and an extensive genetic algorithmic search. Neither search method, with either pathway, could find a combination of transition rates that would reproduce the set of observed co-occurrence frequencies. We conclude that neither the linear pathway, nor the nonlinear pathway considered here, is an adequate description of progression in heterogeneous breast tumors. This quantitative investigation lends support to previous evidence from histopathology and molecular biology that the grades of DCIS and IDC seen together in heterogeneous breast tumors may not be obligate steps in tumor progression.

Safe touch temperatures for hot plates

A finite difference heat transfer model has been developed to predict the Safe Touch Temperatures (STT) for plates made of different materials. SST can be defined as the highest temperature at which no pain is felt when the surface is touched for a long enough period to allow safe handling of the equipment. The criterion used to quantify damage is the "damage function" that was originally proposed by Henriques and Moritz. There are several uncertainties present in the physiological and thermal properties of the skin that give rise to a solution range rather than a single solution. Certain simplifying assumptions are made that tend to yield solutions for STT that are toward the lower or "safe" end of the solution range. The model developed is a two-dimensional axisymmetric model in cylindrical coordinates. A finite difference scheme that uses the Alternating Direction Implicit method is used to solve the problem. It is a second-order scheme in both space and time domains. A parametric analysis of the model is performed to isolate those factors that affect the STT to the greatest extent. Data are presented for a variety of cases, which cover commonly observed ranges in material and geometric properties. It is found that the material properties, namely thermal conductivity and volumetric heat capacity, and the plate thickness ratio are the three most important parameters. These three parameters account for a range of STT from 56 degrees C-100 degrees C with thick metals at the low end and thin metals and plastics in the high range. This method represents a significant improvement over existing standard practices.

Primary sequence of baboon CR1 demonstrates concerted evolution within the CR1 gene

Complement receptor type one (CR1) in primates has several remarkable structural features including a size polymorphism (Mr 190000, 220000, 250000 and 280000) in man, multiple size variants (Mr 55000-220000) among non-human primates, and a partial amino-terminal duplication (CR1-like gene) that appears to encode the short (55000-70000) forms expressed on primate erythrocytes. In general, these short CR1 forms, some of which are GPI anchored, are expressed on erythrocytes and the 220000 molecular weight CR1 form is expressed on PBMC, except in man, where only the 220000 molecular weight form has been detected. In addition, the Mr 220000 human CR1 sequence carries several long internal repeats of up to 99% homology. It has been suggested that the highest homology is maintained by gene conversion and/or unequal crossover. To address further the evolutionary and biologic implications of these multiple forms, a 6 kb cDNA encoding baboon CR1(220) was identified by RTPCR using human CR1 primers. Its sequence contains the expected 30 complement control protein repeats (CCP) and demonstrates an overall homology to human CR1 of 95.4% at the nucleotide level and 93.2% at the amino acid level. As in human CR1, the first 28 CCP maintain the characteristic "seven CCP-long homologous repeats (LHR)" organization. Analysis of baboon CR1(220) indicates that horizontal or concerted evolution has maintained a high degree (> 98%) of identity between corresponding CCP within the LHRs from CCP 4 to CCP 19, while this homology region extends from CCP 3 to CCP 18 in man. In contrast, substitutions occurring in other CCP are not propagated to the corresponding sites of other LHR. Sequence differences in CCP 1, 2 and 3 are likely to be related to the acquisition of enhanced C3b binding capability by this amino-terminal region of the protein. Thus, the sequence data strongly support the hypotheses that gene conversion and or unequal crossover events have driven the evolution of the protein in regions of high homology while selective forces, probably ligand binding requirements, have maintained the regions of divergence.

Combined therapy with verapamil and propranolol in chronic stable angina

The comparative efficacy of verapamil (360 mg daily) and propranolol (240 mg daily) was evaluated with computerized treadmill exercise in 22 patients with chronic stable angina in a placebo-controlled double-blind crossover study with 4 weeks on each active phase. Fourteen of these patients still had angina despite active drug therapy and they were further treated with a combination of verapamil (360 mg) and propranolol (120 mg) for 4 weeks. The mean exercise time for these patients taking placebo was 4.8 +/- 0.22 minutes (mean +/- standard error of the mean) and this increased to 6.8 +/- 0.64 minutes with propranolol and 8.0 +/- 0.5 minutes with verapamil. A further increase to 10.1 +/- 0.88 minutes was observed with the combination of both drugs and seven patients became symptom-free. S-T segment criteria improved with both drugs, and combination therapy produced a further reduction in peak S-T depression. Electrocardiographic ambulatory monitoring showed no evidence of conduction defects and mean hourly heart rates were similar to those seen with propranolol alone. Left ventricular function indexes were not significantly different from those obtained with propranolol. Combination therapy with verapamil and propranolol appears to be efficacious in the treatment of selected patients with severe chronic stable angina. The patients need to be carefully monitored for adverse effects.

Long-term antianginal action of verapamil assessed with quantitated serial treadmill stress testing

The long-term efficacy of verapamil in a dose of 360 mg daily in patients with chronic stable angina pectoris was assessed by quantitated serial treadmill exercise tests. Twenty-eight patients were investigated with a placebo-controlled, double-blind, crossover protocol of 2 weeks each and afterward all patients were put on long-term therapy. Exercise tests were performed at the end of the placebo period and after 2, 4, 8, 16, 24 and 52 weeks of verapamil therapy. All 28 experienced angina during treadmill tests on placebo and the mean (+/- standard error of the mean) exercise time was 6.6 +/- 0.5 minutes. This increased to 9.2 +/- 0.8 minutes at 2 weeks and 50 11.2 +/- 0.8 minutes at 4 weeks. Fifteen and 20 of the 28 patients became angina-free during treadmill exercise at 2 and 4 weeks, respectively. The consumption of nitroglycerin showed a similar improvement. The improvement was maintained at 1 year of follow-up. The on-line computer-analyzed S-T segment changes showed a statistically significant improvement at all follow-up periods. Withdrawal of verapamil produced a return to pretreatment levels. The adverse effects noted were constipation in seven patients and reversible P-R interval prolongation in two. No heart failure occurred in any patient. These findings suggest that verapamil possesses a powerful and sustained antianginal action and, in a dose of 360 mg daily, merits a place as a primary therapeutic agent in the management of chronic stable angina.

Exercise-induced S-T segment elevation in variant angina

Five patients with known ischemic heart disease had an unusual pattern of S-T segment depression during treadmill exercise testing followed by S-T segment elevation and chest pain in the postexercise period. Thallium-201 scintigraphy revealed reversible exercise-induced myocardial ischemia, in areas supplied by severely narrowed coronary arteries as documented by coronary arteriography. Ambulatory electrocardiographic recording for S-T segment shift using a frequency-modulated system showed S-T segment depressions and elevations at rest in the same leads that showed similar shifts during exercise tests. Three of the five patients had a myocardial infarction within 8 weeks of diagnosis, and two died. This syndrome may be associated with severe coronary artery disease and may have a very poor prognosis.