[Outcome of selective mating in the Entlebucher Mountain Dog for reduction of ureteral ectopia]. / Ergebnis der selektiven Verpaarung beim Entlebucher Sennenhund zur Reduktion der ureteralen Ektopie.

INTRODUCTION: The Entlebucher Mountain Dog is predisposed to ureteral ectopia and associated diseases of the urinary tract as well as the kidneys, which can have severe to lethal consequences. Due to the clustered occurrence of clinical signs in 11 % of Entlebucher Mountain dogs in the absence of a genetic test for ureteral ectopia, screening was introduced in 2008 to allow phenotype-based breeding selection. The ureteral orifices of the dogs are visualized by ultrasound and existing urinary retention or urinary incontinence is documented. The diagnostic findings were evaluated centrally with assignment to one of five phenotypes depending on the localization of the ureteral orifices and the renal and ureteral shape. Breeding approval and mating restrictions are the responsibility of the respective breeding associations and predominantly Entlebucher Mountain Dogs with extravesical ectopic ureters and/or clinical signs were excluded from breeding. The effect of phenotype-based selective mating on the incidence of ureteral ectopia and its clinical signs, as well as possible factors influencing the expression of the phenotype, were determined in the birth cohorts after the introduction of screening. Analysis of the data set of 1456 phenotyped Entlebucher Mountain Dogs showed, that at 11 % versus 5 %, males were more frequently assigned to the extravesical phenotype than females. The effect of phenotype-based breeding selection was examined in a subpopulation consisting of phenotyped parents and their offspring (n = 876). The prevalence of the extravesical phenotype decreased from 24 % in the 2005 to 2007 birth cohorts to 1,4 % in the 2015 to 2017 birth cohorts. Since 2015 almost no Entlebucher Mountain Dogs with incontinence, hydroureter or hydronephrosis have been recorded. It was feared that the additional selection measures to control ureteral ectopia in the small Entlebucher Mountain Dog population would intensify the inbreeding increase. However, this has so far remained absent. Therefore, as long as no genetic test is available, it is recommended to continue phenotype-based breeding selection with exclusion of dogs with extravesical ureteral ectopia and/or hydroureter/hydronephrosis/urinary incontinence, while keeping an eye on the development of the inbreeding coefficient.

INTRODUCTION: Le Bouvier de l'Entlebuch est prédisposé à l'ectopie urétérale et aux maladies associées des voies urinaires ainsi que des reins, ce qui peut entraîner des conséquences fatales. En raison de l'apparition de signes cliniques chez 11 % des chiens et en l'absence d'un test génétique pour l'ectopie urétérale, un dépistage a été introduit en 2008 pour permettre une sélection d'élevage basée sur le phénotype. Les orifices urétraux des chiens ont été visualisés par échographie et la rétention ou l'incontinence urinaire existante documentée. Les résultats du diagnostic ont été évalués de manière centralisée avec attribution à l'un des cinq phénotypes en fonction de la localisation des orifices urétéraux ainsi que de la forme des reins et des uretères. L'approbation pour la reproduction et les restrictions d'accouplement relèvent de la responsabilité des associations d'élevage respectives et les bouviers de l'Entlebuch présentant des uretères ectopiques extravésicaux et/ou des signes cliniques ont majoritairement été exclus de la reproduction. L'effet de cet accouplement sélectif basé sur le phénotype sur l'incidence de l'ectopie urétérale et de ses signes cliniques ainsi que les facteurs possibles influençant l'expression du phénotype ont été déterminés dans les cohortes de naissance après l'introduction du dépistage. L'analyse de l'ensemble des données de 1456 Bouviers de l'Entlebuch phénotypés a montré que, à 11 % contre 5 %, les mâles étaient plus fréquemment affectés au phénotype extravésical que les femelles. L'effet de la sélection d'élevage basée sur le phénotype a été examiné dans une sous-population composée de parents phénotypés et de leur progéniture (n = 876). La prévalence du phénotype extravésical est passée de 24 % dans les cohortes de naissance de 2005 à 2007 à 1,4 % dans les cohortes de naissance de 2015 à 2017. Depuis 2015, presque aucun bouvier d'Entlebuch présentant une incontinence, un hydrouretère ou une hydronéphrose n'a été enregistré. Une possible augmentation de la consanguinité due aux mesures de sélection supplémentaires visant à contrôler l'ectopie urétérale ne s'est pas produite. Par conséquent, tant qu'aucun test génétique n'est disponible, il est recommandé de poursuivre la sélection d'élevage basée sur le phénotype avec exclusion des chiens présentant une ectopie urétérale extravésicale et/ou une hydrouretère/hydronéphrose/incontinence urinaire, tout en surveillant l'évolution du coefficient de consanguinité.

X chromosome aneuploidy and micronuclei in fertile mares.

Abnormalities of chromosomes are an important and well documented cause of disorders of sexual development, fertility problems and congenital anomalies in mammals. Detection of low-level 63,X/64,XX mosaicism during routine cytogenetic evaluation is a challenge because its clinical significance is not yet fully clear. This study describes the prevalence and levels of 63,X mosaicism for a cohort of fertile mares and compares the results with eight problem mares for which no clinical cause of sub-fertility was found. The study design allowed for the analysis of micronuclei which are biomarkers of genomic instability and can disturb cell divisions, drive cancer development or cause congenital diseases. Although 27% of the fertile mares were identified to be 63,X mosaics, the results showed that the rates of abnormal cells were very low (1-3%). Levels of abnormal cells in problem mares with 63,X mosaicism were similar or higher. The average rate of micronuclei in the blood of the fertile mares was ∼1%, well below the baseline (5%) which was proposed for peripheral blood of normal healthy humans. We found weak to modest, but not significant, correlations between the age of fertile mares and 63,X cells (Kendall's tau b = 0.2905; p > 0.05) as well as the rate of micronuclei (Kendall's tau b = 0.1896; p > 0.05). Likewise, the correlation between presence of a 63,X cell line and micronuclei rate was not significant (Kendall's tau b = 0.3201; p > 0.05). The presence of 63,X cells in rates greater than 3% may indeed indicate a higher risk for sub-fertility and eventually for associated health problems in such mares. Detection and elimination of mares with high level of X aneuploidies from breeding may have a positive effect on the fertility within the general horse population. This data may support the evaluation of problem mares with mosaic karyotypes involving the X chromosome.

New genomic features of the polled intersex syndrome variant in goats unraveled by long-read whole-genome sequencing.

In domestic goats, the polled intersex syndrome (PIS) refers to XX female-to-male sex reversal associated with the absence of horn growth (polled). The causal variant was previously reported as a 11.7 kb deletion at approximately 129 Mb on chromosome 1 that affects the transcription of both FOXL2 and several long non-coding RNAs. In the meantime the presence of different versions of the PIS deletion was postulated and trials to establish genetic testing with the existing molecular genetic information failed. Therefore, we revisited this variant by long-read whole-genome sequencing of two genetically female (XX) goats, a PIS-affected and a horned control. This revealed the presence of a more complex structural variant consisting of a deletion with a total length of 10 159 bp and an inversely inserted approximately 480 kb-sized duplicated segment of a region located approximately 21 Mb further downstream on chromosome 1 containing two genes, KCNJ15 and ERG. Publicly available short-read whole-genome sequencing data, Sanger sequencing of the breakpoints and FISH using BAC clones corresponding to both involved genome regions confirmed this structural variant. A diagnostic PCR was developed for simultaneous genotyping of carriers for this variant and determination of their genetic sex. We showed that the variant allele was present in all 334 genotyped polled goats of diverse breeds and that all analyzed 15 PIS-affected XX goats were homozygous. Our findings enable for the first time a precise genetic diagnosis for polledness and PIS in goats and add a further genomic feature to the complexity of the PIS phenomenon.

Association of missense variants in GDF9 with litter size in Entlebucher Mountain dogs.

In the past two decades, average litter size (ALS) in Entlebucher Mountain dogs decreased by approximately 0.8 puppies. We conducted a GWAS for ALS using the single-step methodology to take advantage of 1632 pedigree records, 892 phenotypes and 372 genotypes (173 662 markers) for which only 12% of the dogs had both phenotypes and genotypes available. Our analysis revealed associations towards the growth differentiation factor 9 gene (GDF9), which is known to regulate oocyte maturation. The trait heritability was estimated at 43.1%, from which approximately 15% was accountable by the GDF9 locus alone. Therefore, markers flanking GDF9 explained approximately 6.5% of the variance in ALS. Analysis of WGSs revealed two missense substitutions in GDF9, one of which (g.11:21147009G>A) affected a highly conserved nucleotide in vertebrates. The derived allele A was validated in 111 dogs and shown to be associated with decreased ALS (-0.75 ± 0.22 puppies per litter). The variant was further predicted to cause a proline to serine substitution. The affected residue was immediately followed by a six-residue deletion that is fixed in the canine species but absent in non-canids. We further confirmed that the deletion is prevalent in the Canidae family by sequencing three species of wild canids. Since canids uniquely ovulate oocytes at the prophase stage of the first meiotic division, requiring maturation in the oviduct, we conjecture that the amino acid substitution and the six-residue deletion of GDF9 may serve as a model for insights into the dynamics of oocyte maturation in canids.

[Unilateral peromelia of the left pelvic limb in a Brown Swiss calf]. / Unilaterale Peromelie der linken Beckengliedmasse bei einem Brown Swiss Kalb.

INTRODUCTION: Congenital deformities of the limbs occur sporadically in various species, but the cause is often unclear. The clinically healthy female Brown Swiss calf presented here showed a congenital peromelia of the left hind limb. The affected limb is twisted, disproportional and the bones distally of the metatarsus are missing. Karyotyping and genome sequencing did not indicate on a genetic cause of the anomaly. An infection with the Schmallenberg virus could not be ruled out. Furthermore, there was no evidence of further adverse environmental effects during pregnancy.

INTRODUCTION: Des malformations congénitales des membres, dont la cause est souvent peu claire, surviennent sporadiquement chez diverses espèces. Le veau Brown Swiss femelle présenté ici, tout en étant cliniquement sain, présentait une péromélie congénitale du postérieur gauche. Le membre concerné été en rotation interne, disproportionné et les os distalement au métatarse étaient absents. La détermination du caryotype et le séquençage de l'ensemble du génome n'ont apporté aucun élément parlant pour une cause génétique de l'anomalie. Il n'a pas été possible d'exclure une infection par le virus de ­Schmallenberg. D'autre part il n'y avait aucun élément évoquant d'autres influences environnementales néfastes durant la gestation.

[Chromosomal aberrations in a subfertile cotton-top tamarin]. / Chromosomen-Veränderungen bei einem subfertilen Lisztäffchen.

INTRODUCTION: The present case report describes a female cotton-top tamarin which was taken over by the Zoo Basel to form a new breeding pair. The animal demonstrated increased marking behavior without any obvious medical reasons, dominant behavior, failure to become pregnant and its external genitals were ambiguous. A disorder of the sexual development (DSD) was suspected by the zoo veterinarians and in a first step, the chromosomes of the monkey were analyzed. Six cell lines with different karyotypes were observed. The two most frequent cell lines had a 46,XX or a 46,XY karyotype which are normal chromosome complements of female and male cotton-top tamarins, respectively. The other much less frequent cell lines showed numerical aberrations with and without a marker chromosome. Specific biological features of the Callitrichidae, such as natural twinning and genetic chimerism impeded the clarification of the pathogenesis and prevented a reliable prognosis on the fertility of the cotton-top tamarin.

[A case of 63,X/64,XX mosaicism in a subfertile pony mare]. / Ein Fall von 63,X/64,XX Mosaizismus bei einer subfertilen Ponystute.

INTRODUCTION: The present case report describes a 6-year old subfertile pony mare, which became pregnant after the eleventh artificial insemination. The examination of the ovaries and the uterus did not reveal any abnormal clinical findings and the mare showed a regular oestrous cycle. Based on cytogenetic and molecular genetic analyses it became possible to elucidate the observed subfertility. The mosaic karyotype of the mare consisted of 63,X (20%) and 64,XX (80%) cells. A PCR analysis failed to amplify sequences from the equine SRY gene. The observed classic 63,X/64,XX mosaicism is a plausible explanation for the subfertility of the mare.

[A case of SRY positive sex reversal in a domestic cat]. / Ein Fall von SRYpositiver Sex-Umkehr bei einer Hauskatze.

The present case report describes a stray cat with a female appearance. The new owners requested to neuter the animal. During surgery the veterinarian could not find any gonadal tissue. After puberty the cat showed more and more male behaviour. The owners of the cat were interested to know the cause of the abnormal behaviour, but forbid any further clinical tests or surgery. Based upon cytogenetic and molecular genetic experiments a diagnosis became possible. The uniform karyotype (38,XY) was in accordance with the karyotype of a male cat and it was possible to amplify the SR Y gene by PCR. The cat represents a case of SRYpositive sex reversal.

[Cytogenetical and molecular analyses in a horse with SRY-negative sex reversal]. / Zytogenetische und molekulargenetische Abklärungen bei einem Pferd mit SRY-negativer Sex-Umkehr.

Numerical and structural aberrations of chromosomes may cause malformations, embryonal losses and reduced or missing fertility. In male horses the fertility is rather well controlled through their semen evaluation. For mares there are no mandatory regulations which specify their use in a breeding programme. Therefore, mares with chromosomal aberrations, which exclude reproduction success may be chosen for breeding. The present case describes a horse, offically registered as a female, which was presented for a breeding exam. On this occasion, small and inactive ovaries were diagnosed. Although the cytogenetical analysis excluded a numerical or gross structural chromosome aberration, the karyotype (64,XY) corresponded to the male sex. The diagnosis male to female sex-reversal (SRY-negative) excludes reproductive success for this horse. This case underlines the importance of a cytogenetic analysis for female horses, before they enter a breeding programme.

Detection of sex chromosome aneuploidy in equine spermatozoa using fluorescence in situ hybridization.

The aim of our study was to diagnose aneuploidy in equine spermatozoa by multicolour fluorescence in situ hybridization (FISH) technique using specific molecular probes for equine sex chromosomes and autosome pair four (EGFR probe) labeled by different fluorochromes. These were applied on decondensed spermatozoa of four stallions. In total, more than 8800 sperm cells were examined. The total frequency of aberrant cells was 0.496%: aneuploidy of XX (0.135%), YY (0.023%), XY (0.102%), diploidy (0.057%), lack of sex chromosome (0.18%). In one stallion the ratio of normal X- and Y-bearing cells was different from the expected 1:1 ratio (p = 0.0002), in all three other stallions this ratio was close to 1:1. The present study demonstrated that the FISH technique is a powerful method to identify sex chromosome aberrations in equine spermatozoa and allows for the determination of the ratio between X-Y-spermatozoa.

Cytogenetic studies and karyotype nomenclature of three wild canid species: maned wolf (Chrysocyon brachyurus), bat-eared fox (Otocyon megalotis) and fennec fox (Fennecus zerda).

We have analysed the chromosomes of three wild and endangered canid species: the maned wolf (Chrysocyon brachyurus), the bat-eared fox (Otocyon megalotis) and the fennec fox (Fennecuszerda) using classical and molecular cytogenetic methods. For the first time detailed and encompassing descriptions of the chromosomes are presented including the chromosomal assignment of nucleolar organizer regions and the 5S rRNA gene cluster. We propose a karyotype nomenclature with ideograms including more than 300 bands per haploid set for each of these three species which will form the basis for further research. In addition, we propose four basic different patterns of karyotype organization in the family Canidae. A comparison of these patterns with the most recent molecular phylogeny of Canidae revealed that the karyotype evolution of a species is not always strongly connected with its phylogenetic position. Our findings underline the need and justification for basic cytogenetic work in rare and exotic species.

A case of an intersex horse with 63,X/64,XX/65,XX,del(Y)(q?) karyotype.

Cytogenetic and molecular genetic studies of an intersex horse have been carried out. The investigated animal had overall male body conformation; however, its external genitalia consisted of incompletely developed vulva and penis. The X and Y chromosome painting probes detected three cell lines in the examined horse: 63,X, 64,XX and 65,XX with a fragment of a Y chromosome (del Y). The DNA analysis with the PCR and PCR/RFLP methods showed absence of SRY,AMELY and ZFY genes as well as of six Y microsatellite markers (YM2, YP9, YJ10, YE1, YH12, and YA16). These results suggest that the Y chromosome fragment detected in the investigated animal was the result of a deletion of a euchromatic fragment comprising the above-mentioned markers.

The mechanisms determining the nucleolar-organizing regions inactivation of domestic horse chromosomes.

Cytogenetic investigations of the nucleolar-organizing regions (NORs) show that there is variation in the transcriptional activity of rDNA in many organisms. As a consequence, genetic polymorphism of these regions has been detected. The aim of the present study was to evaluate the hypothetic genetic mechanisms determining the NORs polymorphism of the domestic horse chromosomes. Molecular cytogenetic analyses were carried out on Hucul horses and the following techniques were used: fluorescence in situ hybridization (FISH), telomere primed in situ synthesis (PRINS), in situ nick-translation with HpaII, silver staining (AgNOR) and C-banding technique (CBG). The obtained results suggest that variation in the number and size of silver deposits is related to the number of rDNA copies, DNA methylation and the localization of ribosomal DNA loci in telomeric regions. Moreover, we have found that chromosome pairs 28 and 31 are characterized by higher variation in the NORs number.

A canine X chromosome painting probe applied to four canid species: close relationship of a heterochromatic-like sequence between the dog and the blue fox.

Microdissection of chromosomes is an invaluable tool to physically isolate single chromosomes, chromosome-arms or chromosome-bands and, subsequently generate painting probes with which numerical or structural aberrations of chromosomes can be studied. In addition, such painting probes can be used to compare karyotypic relationships among mammalian species. For the present study a canine whole X chromosome painting probe was prepared by means of conventional microdissection and degenerate-oligonucleotide-primed PCR. The application of this paint to the chromosomes of the domestic dog, red fox, blue fox and Chinese raccoon dog revealed hybridization to the entire X chromosome and the pseudo-autosomal region of the Y chromosome in all four species analysed. In the blue fox the same paint revealed additional strong hybridization signals on the heterochromatic arms after low-stringent posthybridization washes. The present study indicates the existence of an ancient canid heterochromatic-like DNA sequence, which survived in the proximal part of the X chromosome of all species studied and, in addition, was involved in the formation of heterochromatic arms in the blue fox.

Dysphagia and multiple sclerosis.

Over 30% of persons with multiple sclerosis (pwMS) suffer from swallowing symptoms, a higher rate than previously assumed. Neurogenic dysphagia (ND) may cause many different kinds of oropharyngeal sensorimotor dysfunctions in pwMS, and is associated with both the amount of disability and brainstem signs. About 15% of pwMS with mild disability may also suffer from ND. Diagnostic tools comprise history taking, bedside screening examination (50 ml water test combined with assessment of pharyngeal sensation or with pulse oximetry) and sometimes a videofluoroscopic swallowing study (VFSS) and fibreoptic endoscopic evaluation of swallowing (FEES). VFSS and FEES are complementary methods and both have advantages and disadvantages. Interventions for ND in pwMS are mainly based on functional swallowing therapy, including methods of restitution, compensation and adaptation. The aim of intervention is to prevent aspiration and aspiration pneumonia. Outcome assessment should focus on clinically relevant parameters, such as activity limitation, participation restriction and health-related quality of life.

Comparison of 26-week efficacy and tolerability of telmisartan and atenolol, in combination with hydrochlorothiazide as required, in the treatment of mild to moderate hypertension: a randomized, multicenter study.

OBJECTIVE: This study was undertaken to compare the efficacy and tolerability of telmisartan, a novel antihypertensive agent, and atenolol, a well-established beta-blocker, in the treatment of mild to moderate hypertension. METHODS: This 26-week, multicenter, randomized, double-blind, double-dummy, parallel-group, titration-to-response study compared doses of telmisartan (40 mg titrated to 80 mg titrated to 120 mg) with atenolol (50 mg titrated to 100 mg) required to achieve diastolic blood pressure (DBP) control (< or = 90 mm Hg or a decrease from baseline of > or = 10 mm Hg). Open-label hydrochlorothiazide (HCTZ) 12.5 or 25 mg was added if needed according to a prespecified titration rule. Men and women aged > 18 years with mild to moderate hypertension (morning mean supine DBP [SDBP] > or = 95 mm Hg and < or = 114 mm Hg) were eligible to participate. Patients with significant cardiovascular, metabolic, hepatic, or renal dysfunction or chronic obstructive pulmonary disease were excluded. The primary efficacy end point was trough SDBP response at 26 weeks; secondary efficacy end points included changes from baseline at trough in both standing and supine DBP and systolic blood pressure (SBP), and heart rate after 4, 8, 16, and 26 weeks; SBP control (reduction from baseline of > or = 10 mm Hg); normalization of supine SDBP to < or = 90 mm Hg; and the need for add-on HCTZ. Changes in quality of life were also examined. Adverse events were obtained from spontaneous reporting and recorded. Serious adverse events were reported to the sponsor according to predefined timelines. RESULTS: A total of 533 patients from 49 centers participated. Patients' mean age was 57.9 years (range, 22-79 years); 55.9% (298/533) of the population was male and 98.1% (523/533) was white. Of the 533 patients randomly assigned to treatment and included in the safety analysis, 520 (97.6%) were included in the efficacy analysis; 346 received telmisartan and 174 received atenolol. A total of 489 patients (91.7%) completed the study (325 [93.9%], telmisartan; 164 [94.2%], atenolol). Full SDBP response (trough SDBP < or = 90 mm Hg and/or a reduction from baseline of > or = 10 mm Hg) was observed in 84% and 78% of telmisartan- and atenolol-treated patients, respectively; this difference was not statistically significant. Final SBP/DBP reductions of 20.9/14.4 mm Hg were observed for the telmisartan regimen versus 16.7/13.3 mm Hg for the atenolol regimen; only the difference in SBP was significant (P = 0.005). Reduction from baseline in SBP of > or = 10 mm Hg was achieved by 80% of telmisartan-treated and 68% of atenolol-treated patients (P = 0.003). Adverse events were reported by 52.7% of patients given telmisartan and 61.2% of patients given atenolol; this difference was not statistically significant. Most events were mild or moderate. Although fatigue and male impotence were more common in atenolol-treated patients (3.4% and 4.0%, respectively), the incidence of these adverse events was too low to differentiate statistically. CONCLUSIONS: Telmisartan appears to be at least as effective as atenolol in the treatment of mild to moderate hypertension and may be better tolerated.

Combination of calcium channel blockers and beta-blockers for patients with exercise-induced angina pectoris: beneficial effect of calcium channel blockers largely determined by their effect on heart rate.

The combination of calcium channel blockers and beta-blockers is more effective for the treatment of exercise-induced angina pectoris than beta-blocker monotherapy. As ischemia in exercise-induced angina is essentially preceded by an increase in heart rate, calcium channel blockers with a negative chronotropic property may perform better for this purpose than nonchronotropic compounds. A 335-patient, 10-week, double-blind, parallel-group comparison of amlodipine 5 mg and 10 mg, diltiazem 200 mg and 300 mg, and mibefradil 50 mg and 100 mg treatment added to baseline beta-blocker treatment was performed. Exercise testing (ETT) was performed by bicycle ergometry. All of the calcium channels blockers significantly delayed the onset of 1 mm ST-segment depression on ETT (p < 0.001 for any treatment vs. baseline). In addition, mibefradil, in both low- and high-dose treatments, produced the largest delays (low dose: different from diltiazem and amlodipine by 24.1 and 29.8 seconds, respectively, p < 0.003 and < 0.001; high dose: different from diltiazem and amlodipine by 33.7 and 37.0 seconds, respectively, p < 0.001 and < 0.001). A stepwise logistic regression analysis revealed that this beneficial effect of calcium channel blockers was largely dependent on their effect on heart rate. Serious symptoms of dizziness likewise occurred significantly more frequently on mibefradil (p < 0.05 vs. diltiazem) and urged no fewer than 19 patients on mibefradil to withdraw from the trial. The authors conclude that calcium channel blockers with a negative chronotropic property provide a better delay of ischemia in patients with exercise-induced angina, but the concomitant risk of intolerable dizziness may reduce this benefit.

Combination of calcium channel blockers and beta blockers for patients with exercise-induced angina pectoris: a double-blind parallel-group comparison of different classes of calcium channel blockers. The Netherlands Working Group on Cardiovascular Research (WCN).

The combination of calcium channel blockers and beta blockers is more effective for the treatment of exercise-induced angina pectoris than beta blocker monotherapy. Since ischemia in exercise-induced angina is essentially preceded by an increase in heart rate, calcium channel blockers with negative chronotropic property may perform better for this purpose than nonchronotropic compounds. A 335-patient, 10-week, double-blind, parallel-group comparison of amlodipine 5 and 10 mg, diltiazem XR 200 and 300 mg, and mibefradil 50 and 100 mg treatment added to baseline beta blocker treatment was performed. Exercise testing (ETT) was performed by bicycle ergometry. Although none of the calcium channel blockers improved duration of exercise or amount of workload, all of them significantly delayed onset of 1 mm ST segment depression on ETT (p<0.001 for any treatment versus baseline). In addition, mibefradil, both low- and high-dose treatment, produced the largest delays (low dose: different from diltiazem and amlodipine by 24.1 and 29.8 s, p<0.003 and <0.001, respectively; high dose: different from diltiazem and amlodipine by 33.7 and 37.0 s, p<0.001 and <0.001, respectively). These effects were linearly correlated to the amount of rate pressure product (RPP) reduction. Serious symptoms of dizziness likewise occurred significantly more frequently with mibefradil (p<0.05) and led 19 patients taking mibefradil to withdraw from the trial. The authors conclude that calcium channel blockers with negative chronotropic property provide better delay of ischemia in patients with exercise-induced angina but that the concomitant risk of intolerable dizziness largely reduces this benefit.

Combination of calcium channel blockers and beta-adrenoceptor blockers for patients with exercise-induced angina pectoris: a double-blind parallel-group comparison of different classes of calcium channel blockers. Netherlands Working Group on Cardiovascular Research (WCN).

AIMS: The combination of calcium channel blockers and beta-adrenoceptor blockers is more effective for the treatment of exercise-induced angina pectoris than beta-adrenoceptor blocker monotherapy. As ischaemia in exercise-induced angina is preceded by increase in heart rate, calcium channel blockers with negative chronotropic properties may perform better for this purpose than nonchronotropic compounds. METHODS: A 335 patient double-blind parallel-group study comparing 14 day treatment with amlodipine 5 and 10 mg, with diltiazem 200 and 300 mg, and mibefradil 50 and 100 mg added to baseline beta-adrenoceptor blocker treatment was performed. Exercise testing (ETT) was performed by bicycle ergometry. RESULTS: Although none of the calcium channel blockers improved duration of exercise or amount of workload, all significantly delayed onset of 1 mm ST-segment depression on ETT (P<0.001 for any treatment vs baseline). In addition, mibefradil, both low and high dose treatment, produced the longest delays (low dose: different from diltiazem and amlodipine by 24.1 and 29.8 s, respectively, P<0. 003 and <0.001; high dose: different from diltiazem and amlodipine by 33.7 and 37.0 s, respectively, P<0.001 and <0.001). These effects were linearly correlated with the reduction in rate pressure product (RPP). Serious symptoms of dizziness occurred significantly more frequently on mibefradil (P<0.05), and 19 patients on mibefradil withdrew from trial. CONCLUSIONS: Calcium channel blockers with negative chronotropic properties provide greater delay of ischaemia in patients with exercise-induced angina, but the concomitant risk of intolerable dizziness attenuates this benefit.

A randomised, double-blind trial comparing mibefradil and amlodipine: two long-acting calcium antagonists with similar efficacy but different tolerability profiles. Mibefradil International Study Group.

OBJECTIVE: To compare the efficacy and tolerability of mibefradil and amlodipine in patients with uncomplicated mild-to-moderate essential hypertension. DESIGN: A double-blind, randomised, parallel group multicentre trial. METHODS: 239 patients received 50 mg mibefradil or 5 mg amlodipine for 4 weeks, followed by a forced titration to 100 mg mibefradil or 10 mg amlodipine for an additional 8 weeks. Patients then entered a 4-week withdrawal period either on therapy or switched to placebo. RESULTS: Statistically equivalent reductions in trough sitting diastolic blood pressure (SDBP) were observed after 12 weeks of once-daily treatment with 50/100 mg mibefradil (-11.5 +/- 8.2 mm Hg) and 5/10 mg amlodipine (-13.2 +/- 7.9 mm Hg). The number of patients with normalised SDBP (< or = 90 mm Hg) increased 23.3% in the mibefradil group and 19.5% in the amlodipine group (approximately 74% in both groups). Patients on mibefradil or amlodipine during the withdrawal period had significantly larger decreases in SDBP than those on placebo. Patients on mibefradil had a decrease in heart rate of 5.5 bpm. Patients on amlodipine had no change in heart rate; however, cessation of amlodipine was associated with a decrease in heart rate. CONCLUSIONS: Mibefradil was as effective as amlodipine in reducing BP; both compounds were effective treatments of hypertension.