Combination of phenotype and polygenic risk score in breast cancer risk evaluation in the Spanish population: a case -control study.

BACKGROUND: In recent years, the identification of genetic and phenotypic biomarkers of cancer for prevention, early diagnosis and patient stratification has been a main objective of research in the field. Different multivariable models that use biomarkers have been proposed for the evaluation of individual risk of developing breast cancer. METHODS: This is a case control study based on a population-based cohort. We describe and evaluate a multivariable model that incorporates 92 Single-nucleotide polymorphisms (SNPs) (Supplementary Table S1) and five different phenotypic variables and which was employed in a Spanish population of 642 healthy women and 455 breast cancer patients. RESULTS: Our model allowed us to stratify two groups: high and low risk of developing breast cancer. The 9th decile included 1% of controls vs 9% of cases, with an odds ratio (OR) of 12.9 and a p-value of 3.43E-07. The first decile presented an inverse proportion: 1% of cases and 9% of controls, with an OR of 0.097 and a p-value of 1.86E-08. CONCLUSIONS: These results indicate the capacity of our multivariable model to stratify women according to their risk of developing breast cancer. The major limitation of our analysis is the small cohort size. However, despite the limitations, the results of our analysis provide proof of concept in a poorly studied population, and opens up the possibility of using this method in the routine screening of the Spanish population.

Cutaneous involvement in an 8-year-old boy with Ras-associated autoimmune leucoproliferative disorder (RALD).

Ras-associated autoimmune leucoproliferative disorder (RALD) is a nonmalignant syndrome associated with somatic KRAS mutations. We report a patient with RALD and cutaneous lesions, the first such case reported, to our knowledge. An 8-year-old boy presented with erythematous plaques on his face and body, along with lymphadenopathies and spleen enlargement without systemic symptoms. An increased number of monocytes were found in skin biopsy, peripheral blood and bone marrow (BM). Juvenile myelomonocytic leukaemia (JMML) was suspected. Genetic study using peripheral blood showed no mutations in the KRAS, PTPN11, NRAS, CBL or BCR-ABL genes, but bone marrow analysis revealed a mutation (p-G12S/c.34 G>A) in the KRAS gene. The karyotype was normal. No KRAS mutations were found using molecular analysis of saliva. The diagnosis of RALD was proposed. The differential diagnosis between RALD and JMML is challenging because there are no established criteria to differentiate between them. The clinical course of RALD is uncertain, so long-term follow-up is recommended.

[Rett syndrome: double epidural catheter for the control of postoperative pain after scoliosis surgery. A literature review]. / Síndrome de Rett: doble catéter epidural para control del dolor postoperatorio tras cirugía de escoliosis. Revisión de la bibliografía.

Rett syndrome is a severe and incapacitating neurological disease caused by a structural defect in the short arm of the X chromosome (Xq28). It affects females and consists of multiple and progressive neurological impairments that start from a young age, leading to lifelong disability and dependency. Scoliosis appears in more than 50% of patients and requires surgical correction in cases where the curvature is severe. Pre-anaesthetic assessment is essential in order to identify the risk factors and thus reduce the morbidity and mortality associated with the surgical procedure. We present the case of a patient affected by this syndrome and scoliosis, who was scheduled to have an instrumented thoracolumbar spine arthrodesis with general anaesthesia, which passed without incident. We evaluate the specific details of this syndrome, its potential complications, and its management from an anaesthetic point of view, emphasising the control of postoperative pain using a double epidural catheter with an infusion of local anaesthetics and fentanyl.

SEA 2022 Standards for Global Control of Cardiovascular Risk. / Estándares SEA 2022 para el control global del riesgo cardiovascular.

One of the objectives of the Spanish Society of Arteriosclerosis is to contribute to better knowledge of vascular disease, its prevention and treatment. It is well known that cardiovascular diseases are the leading cause of death in our country and entail a high degree of disability and health care costs. Arteriosclerosis is a multifactorial disease and therefore its prevention requires a global approach that takes into account the different risk factors with which it is associated. Therefore, this document summarizes the current level of knowledge and includes recommendations and procedures to be followed in patients with established cardiovascular disease or at high vascular risk. Specifically, this document reviews the main symptoms and signs to be evaluated during the clinical visit, the laboratory and imaging procedures to be routinely requested or requested for those in special situations. It also includes vascular risk estimation, the diagnostic criteria of the different entities that are cardiovascular risk factors, and makes general and specific recommendations for the treatment of the different cardiovascular risk factors and their final objectives. Finally, the document includes aspects that are not usually referenced in the literature, such as the organization of a vascular risk consultation.

[Efficacy and safety of ezetimibe in vascular risk units]. / Eficacia y seguridad de ezetimiba en unidades de riesgo vascular.

OBJECTIVES: This study was intended to assess the efficacy and safety of ezetimibe when taken alone or combined with statins in a specialized care setting and under standard clinical practice conditions. PATIENTS AND METHODS: A multicenter, retrospective study in patients with dyslipidemia seen in a specialized outpatient clinic and treated with ezetimibe for at least 12 weeks. Patients were divided into three groups: monotherapy, add-on ezetimibe, and initial coadministration. RESULTS: A total of 217 patients (mean age 59 years; 37% ≥65 years) were enrolled. Of these, 61% were women, 21% had type 2 diabetes and 20% had had a previous cardiovascular event so that the lipid lower drug treatment should satisfy the objectives of secondary prevention. Mean change in the monotherapy group (n = 92; mean 41 weeks) included: decrease of LDLc of 28% (P <.001). In the group where ezetimibe was added on to different ongoing statins (n = 94, mean 73 weeks), mean changes was as follows: LDLc -34%, significant change as compared to monotherapy (P < .001). In the group with initial coadministration of ezetimibe with different statins (n = 31; mean 118 weeks), mean change included: LDLc -53% (P < .001). Overall, 64% of patients reached the thereapeutic objective proposed for the Adult Treatment Panel III (ATPIII) for cLDL. In patients with low risk (LDLc < 160 mg/dL), moderate risk (LDLc < 130 mg/dL) and high-very high risk (LDLc < 100-70 mg/dL), the percentage of patients who reached the therapeutic objective was 81%, 64% and 44%, respectively. CONCLUSIONS: Under standard clinical practice conditions, ezetimibe appears to be effective and safe for the control LDLc, thus making it possible to reach the therapeutic objectives proposed by the ATP-III in a high number of patients, especially when associated to statins.

Persistent increase in brain serotonin turnover after chronic administration of LSD in the rat.

Lysergic acid diethylamide at doses of 20 micrograms per kilogram per day was administered orally to rats for I month. Eighteen hours after the final dose a 25 to 30 percent increase in the synthesis and turnover of serotonin was noted, as well as a moderate but significant increase in the concentration of tryptophan (18 percent) and serotonin (13 percent) in the brain.

Ionic chemistry of tetravinylsilane cation (TVS+) formed by electron impact: theory and experiment.

We performed experimental and ab initio studies on tetravinylsilane cation (TVS(+)) and its ionic and neutral fragmentation products. The aim of the study is the assignment of the products formed in electron impact ionization reaction of TVS. The experimental data were compared with ab initio data calculated at the MP2/cc-pVDZ level of theory. We found good agreement between the calculated reaction enthalpies and experimental appearance energies of the ions. More generally, our calculations reveal that there is a competition between intramolecular isomerization and fragmentation processes occurring after ionization of TVS, leading to the formation of a multitude of neutral and ionic species important for characterizing the silicon-carbon-containing plasma and media. New routes for the synthesis of bearing silicon molecules are suggested.

[Haemophagocytic syndrome: A common pathogenic mechanism of various aetiologies]. / Síndrome hemofagocítico: expresión de diversas entidades nosológicas.

INTRODUCTION: Haemophagocytic syndrome (HPS) is a rare syndrome characterised by the uncontrolled activation and proliferation of histiocytes and T cells, leading to a cytokines overproduction. There are two forms of HPS: primary and secondary. OBJECTIVE: To analyse patients diagnosed with HPS at the Oncohaematology Department, using HLH-94 and 2004 protocol diagnostic criteria. MATERIALS AND METHODS: Retrospective study of clinical files of patients diagnosed with HPS, analysing the following features: diagnostic criteria, variability in clinical presentation, aetiology, treatment and outcome. RESULTS: Twenty-two patients were diagnosed with HPS: 6 familial haemophagocytic lymphohistiocytosis (FHL), 11 HPS with evidence of infection, 3 HPS associated with malignant disease and 2 macrophage activation syndrome (MAS) in patients with Crohn's disease and Juvenile Idiopathic Arthritis. The onset of FHL was within 1 year of age in 83.3%, except for 1 patient who was adolescent (MUNC13-4 mutations). SYMPTOMS: All patients (100%) had fever at diagnosis, 18 (85%) hepatosplenomegaly, 7 (31%) lymphadenopathy, 5 (21%) pallor, 3 (14%) rash and 3 (14%) neurological symptoms. LABORATORY ANALYSIS: all patients (100%) had cytopenias at diagnosis, 20 (90.9%) hypertriglyceridaemia, 19 (86%) hyperferritinaemia, 17 (77%) elevated serum liver enzymes, and 9 (40%) hypofibrinogenaemia. Decreased or absent NK-cell activity was detected in all patients (100%). Haemophagocytosis was found more frequently in bone marrow; however, liver or lymph node biopsies were required in two patients to demonstrate this. OUTCOME: Of the ten patients (6 FHL, 3 Epstein-Barr virus-associated HPS and 1 MAS) treated with HLH-94 and 2004 protocols, six received a stem-cell transplant; of these, 2 with FHL had a favourable outcome. The remaining 12 patients received aetiological/supportive therapy, with complete remission in 83.3%. CONCLUSIONS: The diagnosis of FHL should be made before the age of 2 years. Advances in genetic studies allow the detection of early and late forms of FHL. Immunochemotherapy and stem-cell transplantation constitute the treatment of FHL and aetiological/supportive therapy of acquired haemophagocytic lymphohistiocytosis, except in severe forms.

From State-to-Trait Meditation: Reconfiguration of Central Executive and Default Mode Networks.

While brain default mode network (DMN) activation in human subjects has been associated with mind wandering, meditation practice has been found to suppress it and to increase psychological well-being. In addition to DMN activity reduction, experienced meditators (EMs) during meditation practice show an increased connectivity between the DMN and the central executive network (CEN). However, the gradual change between DMN and CEN configuration from pre-meditation, during meditation, and post-meditation is unknown. Here, we investigated the change in DMN and CEN configuration by means of brain activity and functional connectivity (FC) analyses in EMs across three back-to-back functional magnetic resonance imaging (fMRI) scans: pre-meditation baseline (trait), meditation (state), and post-meditation (state-to-trait). Pre-meditation baseline group comparison was also performed between EMs and healthy controls (HCs). Meditation trait was characterized by a significant reduction in activity and FC within DMN and increased anticorrelations between DMN and CEN. Conversely, meditation state and meditation state-to-trait periods showed increased activity and FC within the DMN and between DMN and CEN. However, the latter anticorrelations were only present in EMs with limited practice. The interactions between networks during these states by means of positive diametric activity (PDA) of the fractional amplitude of low-frequency fluctuations (fALFFs) defined as [Formula: see text] revealed no trait differences but significant increases during meditation state that persisted in meditation state-to-trait. The gradual reconfiguration in DMN and CEN suggest a neural mechanism by which the CEN negatively regulates the DMN and is probably responsible for the long-term trait changes seen in meditators and reported psychological well-being.

Clinical and pathological factors associated with the development of hepatocellular carcinoma in patients with hepatitis virus-related cirrhosis: a long-term follow-up study.

AIMS: Hepatocellular carcinoma (HCC) represents >90% of primary liver neoplasms and develops mainly in patients with liver cirrhosis. Risk factor identification for the development of HCC in patients with cirrhosis possesses great clinical relevance due to its high incidence and poor prognosis when detected at advanced stages. The aim of this study was to identify HCC development-associated risk factors in a cohort of patients with hepatitis virus-related chronic liver disease and cirrhosis. MATERIALS AND METHODS: Patients with a diagnosis of hepatitis virus-related cirrhosis between January 1980 and January 2000 were included. Patients were followed with an abdominal ultrasound and the determination of alpha-fetoprotein levels, a physical examination, and routine biochemical tests every 3-6 months. The end point of the study was defined as the development of HCC. Liver histology was evaluated according to the French METAVIR Cooperative Study Group (METAVIR) score. RESULTS: Two hundred and eighty-two patients met the inclusion criteria; most of these (86%) had a serologic diagnosis of hepatitis C virus, and only 14% had hepatitis B virus at the time of the diagnosis of cirrhosis, whereas 56 and 37% were classified as Child A and B, respectively, and only 7% as Child C. Histological activity was mild in 59% of patients, and moderate and severe in 41%. The mean annual incidence was 1.87%, and 22 and 35% of patients developed HCC at 10 and 15 years of follow-up, respectively. The diagnosis of HCC was made by histopathology in 37% and by tumoural lesion-associated alpha-fetoprotein elevation confirmed by imaging studies in 63%. In multivariate analysis, we found three variables associated with HCC: moderate to severe histological activity; a platelet count <105x10(3)/mm(3), and alpha-fetoprotein >5 ng/ml. The patients were divided into two groups according to regression coefficient: low and high risk; patients assigned to the low-risk group showed 5-, 10- and 15-year HCC incidences of 3.4, 6.4 and 6.4%, respectively, in contrast to patients from the high-risk group, who showed incidences of 17.8, 33.5 and 56.8%, respectively. CONCLUSIONS: We found three HCC-associated variables: histological activity, platelet count and alpha-fetoprotein levels. Patients considered as high risk for developing HCC must be considered candidates for closer follow-up.

[Pyelonephritis and pregnancy. Our experience in a general hospital]. / Pielonefritis y embarazo. Experiencia durante un año en un hospital general.

OBJECTIVE: The incidence of pyelonephritis during pregnancy reaches 2%. We recommend obtaining a urinalysis during the first trimester in order to detect asymptomatic bacteriuria and treat those cases with positive urine culture. METHODS: We retrospectively reviewed all cases diagnosed as acute pyelonephritis in pregnant women admitted to our hospital during 2004 and analyzed demographic data, diagnostic methods, treatments, outcome, new episodes and the impact on the date of birth and the newborn. RESULTS: We studied all the cases of pyelonephritis in pregnant women diagnosed in our hospital for one year (4,700 childbirths). We found that screening of bacteriuria was done incorrectly based on the presence of pyuria in the sediment of urine specimen. The incidence was 0.21 %, and such a low rate might be related to the possibility that some patients were not admitted in our hospital. Prognosis was excellent being E. coli the only agent isolated in all cases. Pyelonephritis that occurred during the first trimester relapsed. CONCLUSIONS: A urine culture must be obtained during the first trimester of pregnancy and should be repeated after completion of adequate therapy of an infection, particularly if bacteriuria is detected in the first trimester.

Can bacterial translocation be a beneficial event?

Infection is a major concern in intestinal transplant recipients. Bacterial migration to extraintestinal sites is a central component of the gut hypothesis of sepsis. However, some studies have cited the beneficial effects of bacterial translocation (BT) on the host acquired immune system. We evaluated the role of previous BT on a subsequent BT challenge, examined the BT index in organs as well as changes in white blood cell (WBC) count in mesenteric lymph and blood for correlation with outcomes. Wistar rats (n = 60) were divided into a BT group (n = 20), which underwent inoculation of 10 mL of 10(10) CFU/mL Escherichia coli R-6 confined to the small intestine as opposed to a BT1-14 group (n = 20), which underwent the BT procedure on days 1 and 14 or a S1-BT14 group (n = 20) that received 10 mL of saline on day 1 and the BT procedure on day 14. Half of the animals were killed 2 hours following the BT procedure. Samples from different compartments were collected for culture. Mesenteric lymph and peripheral blood were examined for WBC counts. The other half of the hosts was subjected to outcome evaluation concerning weight gain and mortality. Animals undergoing double BT showed a significantly lower index of bacterial recovery (liver, spleen, and blood) compared with those having a single BT (P < .05). The WBC count of mesenteric lymph cells after double BT was similar to naïve animals, but significantly lower than the single BT group (P < .05). The outcome was unchanged among double BT versus other groups. A previous BT challenge was efficient to generate a host-defense mechanism against a second BT episode induced by intestinal overgrowth with the same bacterial strain.

Surface freezing of water.

Freezing, melting, evaporation and condensation of water are essential ingredients for climate and eventually life on Earth. In the present work, we show how surface freezing of supercooled water in an open container is conditioned and triggered-exclusively-by humidity in air. Additionally, a change of phase is demonstrated to be triggered on the water surface forming surface ice crystals prior to freezing of bulk. The symmetry of the surface crystal, as well as the freezing point, depend on humidity, presenting at least three different types of surface crystals. Humidity triggers surface freezing as soon as it overpasses a defined value for a given temperature, generating a plurality of nucleation nodes. An evidence of simultaneous nucleation of surface ice crystals is also provided.

Differences in epitope restriction of autoantibodies to native human insulin (IAA) and antibodies to heterologous insulin (IA).

The binding profiles of insulin autoantibodies (IAA) and insulin antibodies (IA) to highly purified species variants and fragments of insulin were studied in direct immunospecific enzyme-linked immunosorbent assay (ELISA) and indirect absorption experiments with insulins covalently coupled to Sepharose beads. Five of 10 IAA-containing sera from insulin-naive nondiabetics that bound whole human (H) insulin did not bind whole porcine (P) or whole bovine (B) insulins. These sera bound H insulin B-chain but not P B-chain or desalanated P insulin, suggesting they were dependent on the presence of threonine B30. The other 5 IAA-containing sera bound H, P, B, and desalanated porcine insulins, but only 1 bound isolated B-chains. All 10 IA-containing sera from insulin-treated diabetics bound H, P, B, and desalanated P insulins, but only 1 bound to human (and porcine) B-chain. Further binding studies with ovine, rabbit, rat, and guinea pig insulins confirmed the H (threonine B30) specificity of the 5 IAA-containing sera. B30 residues do not appear to be dominant, however, when insulin is administered exogenously. Instead, IA bind predominantly to A-chain or conformational determinants involving both chains. Scatchard analysis of a representative H insulin-specific IAA serum suggested that it contained a single binding affinity, whereas analysis of a representative IA-diabetic serum suggested it contained several different affinities.

T-lymphocyte lines specific for glutamic acid decarboxylase (GAD) the 64K beta-cell antigen of IDDM.

Insulin-dependent diabetes mellitus (IDDM) is viewed as a thymus-dependent autoimmune disease, although the specific beta-cell autoantigen or autoantigens remain unknown. The recent identification of the beta-cell 64K antigen as the enzyme glutamic acid decarboxylase (GAD) permits investigation of GAD as a candidate for the autoantigen associated with beta-cell destruction, mediated by T-lymphocytes, in susceptible individuals. In this study, we describe the isolation of GAD-specific T-lymphocyte lines from BB rats, an animal model of IDDM. GAD (Escherichia coli) was inoculated into the footpads of diabetes-resistant BB rats, and after 10 days, a popliteal lymph node cell culture suspension was prepared. GAD-specific T lymphocytes were obtained by culture with interleukin 2 and repeated stimulation with GAD in the presence of BB rat thymic antigen-presenting cells. Four stable, CD4+, MHC (RT1u)-restricted T-lymphocyte lines were isolated. They proliferate selectively in the presence of GAD and secrete interleukin 2 and interferon-gamma. T-lymphocyte lines such as these could be important in the definition of pathogenetic epitopes associated with GAD.

Systematic variation and differences in insulin-autoantibody measurements.

Insulin autoantibodies (IAAs) are currently the subject of intensive investigation as potential markers for autoimmune insulitis. However, the results of different reports vary widely. In an attempt to elucidate the reasons for the discrepant reports and to initiate standardization procedures, the International Diabetes Workshop (IDW) undertook two studies in which 22 centers worldwide measured IAA in coded samples. The variance in binding signal from the 49 sera in study 1 was considerable, even when results were standardized, but was largely systematic and attributable to basic differences in assay type (liquid phase versus solid phase) and to differences in the ligand used (human vs. nonhuman insulin). In study 2, 5 sera were prepared and presented blindly to compare dilution curves, insulin-species specificity, interference from irrelevant serum proteins, precision, and dose-dependent displaceability. Many assays, both liquid and solid phase, were influenced by marked and unpredictable nonspecific binding, revealed by loss of parallelism between dilution curves in pooled normal serum and buffer, by variable binding signals with different normal sera, and by difficulty in distinguishing human insulin-specific from cross-reactive IAA sera. It was concluded from the experience of both studies that variance could probably be reduced by using a standard curve with derived common units, a single species of ligand, and methodology to minimize the effect of nonspecific binding. Variation related to assay type was probably due to liquid- versus solid-phase systems being differentially more sensitive to certain aspects of antigen-antibody binding; this issue will be addressed in future serum exchanges and workshops.

Spontaneous hypoglycemia associated with autoimmunity specific to human insulin.

A 55-yr-old woman with a history of Graves' disease experienced attacks of postprandial hypoglycemia for 6 yr. An insulinoma could not be confirmed by repeated fasting tests and by surgical pancreas revision. Extracted pancreatic insulin was chemically normal. Fasting plasma total insulin (1.22 nM = 183 microU/ml) and proinsulin (0.48 nM) were elevated and greatly increased after oral glucose. Glucose-clamp studies revealed delayed insulin clearance. Plasma free-insulin levels were normal. Insulin-binding antibodies were detected by enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay with human insulin as ligand but not with pork or beef insulins. Analysis with a modified ELISA suggested a monotypic and monoclonal human insulin autoantibody, which showed a restriction to the lambda-light chain. T-lymphocytes (predominantly helper) demonstrated increased responsiveness to beef, pork, and human insulins by proliferation assay. A T-lymphocyte line showed exclusively human insulin specificity. All this indicated cellular and humoral anti-human insulin autoimmunities. Clinically, the cause of hypoglycemia associated with elevated total insulin and proinsulin was misdiagnosed as atypical insulinoma. The study of total and free plasma insulin levels and sensitive antibody assays specific to human insulin were necessary to correctly diagnose autoimmune hypoglycemia.

Developments in immunotherapy for gastrointestinal cancer.

Gastrointestinal (GI) cancers are the most commonly occurring cancer worldwide. Colorectal cancer (CRC) is the second and third most commonly diagnosed cancer in women and men, respectively. Despite the advent of screening and the declining incidence of CRC overall, most patients are not diagnosed at an early, localized stage. Due to resistance to chemotherapy, recurrence, and metastatic disease, those diagnosed with advanced disease have only a 12% 5-year survival rate. Given the overwhelming global impact of CRC, the need for advanced therapy is crucial. Targeted immunotherapy in addition to surgical resection, traditional chemotherapy, and radiation therapy is on the rise. For the purpose of this review, we focused on the advances of immunotherapy, particularly in CRC, with mention of research pertaining to particular advances in immunotherapy for other aspects of the GI system. We review basic immunology and the microenvironment surrounding colorectal tumors that lead to immune system evasion and poor responses to chemotherapy. We also examined the way these obstacles are proving to be the targets of tumor specific immunotherapy. We will present current FDA approved immunotherapies such as monoclonal antibodies (mAb) targeting tumor specific antigens, as well as vaccines, adoptive cell therapy, cytokines, and check-point inhibitors. A summation of prior research, current clinical trials, and prospective therapies in murine models help delineate our current status and future strategies on CRC immunotherapy.

Antihypertensive activity of verapamil: impact of dietary sodium. The VERSAL Study Group.

OBJECTIVE: To define the influence of dietary salt intake on the antihypertensive effect of slow-release verapamil 240 mg once a day in a population with mild-to-moderate essential hypertension. DESIGN: Parallel, randomized, multicentre study. METHODS: Patients were advised to follow a moderately low salt diet (Low-salt group). After a 2-week run-in period, those patients with 24-h urinary sodium excretion (UNa) < or = 120 mmol/day and a diastolic blood pressure (DBP) between 90 and 114 mmHg were randomly assigned to verapamil + Low-salt or verapamil + unrestricted-salt diet (High-salt group) for 28 days. Compliance with diets was defined as Low-salt UNa < or = 120 mmol/day and High-salt UNa > 120 mmol/day with UNa increased by > or = 60 mmol/day over the level attained at the end of the run-in period. RESULTS: Significant reductions in mean systolic blood pressure (SBP) and DBP were found in both the Low-salt (n = 235) and High-salt (n = 183) groups. The therapeutic goal (DBP < 90 mmHg) was achieved in 38.3% of patients in the Low-salt and 44.8% of patients in the High-salt group. Office blood pressure results were confirmed by ambulatory 24-h blood pressure monitoring in a subsample of patients. Verapamil reduced mean blood pressure throughout the nycthemeral cycle without any significant difference between the two groups. CONCLUSION: The restriction in sodium intake does not have an additive effect on the antihypertensive effect of the slow-channel calcium antagonist verapamil.