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PubMed1980

Schistosoma mansoni: the ultrastructure of the ducts of the male reproductive system.

The reproductive duct of the male blood fluke Schistosoma mansoni is relatively short and undulating, extending from the most posterior testis to the beginning of the gynecophoric canal. The reproductive duct may be divided into 3 main regions which differ in ultrastructure; the vas efferens/deferens, the seminal vesicle and the cirrus tube. The epithelium of the vas efferens/deferens consists of a single layer of elongate cells with abundant convoluted lamellae on their apical surfaces. The wall of the seminal vesicle and the circus tube are tegumentary in nature. The basic similarities in structure of the surface tegument, the seminal vesicle and the cirrus tube suggest a common embryological origin. The presence of complex lamellae on the luminal surface suggests that the vas efferens and deferens have secretory and possibly nutritive functions apart from temporarily storing developing germ cells. The primary function of the seminal vesicle appears to be that of sperm storage; while the cirrus tube with its complex infolded wall is extensible for insemination. The presence of abundant concentrically distributed sensory papillae around the male genital pore may assist in the pairing of males and females.

Animals↗
PubMed2000

Two new species of Caryospora Léger, 1904 (Apicomplexa, Eimeriidae) from accipitrid raptors.

Two new species of Coccidia (Apicomplexa: Eimeriidae) are described from European accipitrid raptors (Falconiformes: Accipitridae). Oöcysts of Carvospora aquilae n. sp. found in faeces of the gold eagle Aquila chrysaetos are subspherical to broad ellipsoidal and measure 43 (40-49) x 37.5 (34-39) microm. Polar granule, oöcyst residuum and micropyle are absent. Each oöcyst contains one spherical to subspherical slightly polygonal sporocyst measuring 23.8 (23-25) x 23.3 (22-25) microm. Stieda and substieda bodies are absent. The sporocyst residuum is composed of numerous small granules less than 0.5 microm in diameter dispersed randomly among the sporozoites. Sporulated oöcysts of Carvospora circi n. sp. from faeces of the marsh harrier Circus aeruginosus are widely oval, measuring 24.5 (23-25) x 21.8 (21-24) microm. A polar granule, oöcyst residuum and micropyle are absent. Each oöcyst contains one spherical to subspherical sporocyst measuring 16.2 (15-17) x 15.6 (15-17) microm. A compact granular, spherical to subspherical sporocyst residuum, 10.4 (10-11) x 8.5 (7-9), was present in 76% of measured sporocysts. In 24% of sporocysts the granules of sporocyst residuum were scattered among the sporozoites.

Animals↗
PubMed1998

Effect of flecainide on heart rate variability in subjects without coronary artery disease or congestive heart failure.

Heart rate variability is a noninvasive indicator of autonomic nervous system activity. The role of the autonomic nervous system in the genesis of atrial or ventricular arrhythmias is now well established. Little is known about the effects of flecainide on heart rate variability in patients with normal heart structure, the main population receiving flecainide. This study was designed to evaluate the effects of flecainide on heart rate variability in patients without coronary artery disease or congestive heart failure. Time and frequency domain analysis of heart rate variability on 24-hour electrocardiogram recording were assessed in 40 patients with normal echocardiography and without evidence of coronary artery disease before and after 2 months of oral treatment with flecainide (321 +/- 57 mg/day) prescribed for Wolff Parkinson White syndrome with circus movement tachycardia. Flecainide significantly decreased all parameters of heart rate variability in the time domain (median delta% -10% to -25%) and in the frequency domain (median delta% -27% to -38%), including the markers of vagal activity. There was no correlation between plasma concentrations of flecainide and reduction in heart rate variability. It was concluded that in subjects without coronary artery disease or congestive heart failure, flecainide decreases all the measurements of heart rate variability and this decrease is not related to plasma concentrations of flecainide.

Adolescent↗
PubMed2002

Assessment of risks of brodifacoum to non-target birds and mammals in New Zealand.

The risks to non-target birds and other wildlife from the use of vertebrate pesticides, including anticoagulant rodenticides, are determined to a significant extent by species' intrinsic susceptibility, and the toxicokinetics of the compounds used. Brodifacoum is highly toxic to birds and mammals. The acute toxicity of brodifacoum to birds in New Zealand varies from <1 mg/kg in pukeko (Porphyrio p. melanotus), the native swamp hen, to >20 mg/kg in the paradise shelduck (Tadorna variegata). Like other second-generation anticoagulants brodifacoum is strongly bound to vitamin K epoxide reductase and will persist, apparently for at least 6 months, in organs and tissue containing this enzyme, e.g., liver, kidney, and pancreas. The unique toxicokinetics of this class of compound exacerbates the risk of primary and secondary poisoning of non-target species. Vertebrate pest control programmes in New Zealand using bait containing brodifacoum have resulted in the primary and secondary poisoning and sub-lethal contamination of non-target species. These include native raptors, such as the Australasian harrier (Circus approximans) and morepork (Ninox novaeseelandiae), other native birds such as the pukeko, weka (Gallirallus australis), southern black-backed gull (Larus dominicanus), and kiwi (Apteryx spp.), and introduced mammals, including game animals. There are increasing numbers of reports worldwide of wildlife contamination and toxicosis after the use of second-generation anticoagulants. All pest control activities require careful risk-benefit assessment in view of their potential to cause adverse environmental impact. Monitoring of wildlife for pesticide residues will provide data that can be used to reduce the risk of anticoagulant bioaccumulation and mortality in non-target species.

4-Hydroxycoumarins↗
PubMed2002

Non-invasive characteristics of atrial fibrillation: the value of Holter recordings for the treatment of AF.

Atrial fibrillation (AF) is the most common arrhythmia in man associated with significant morbidity and excess mortality. AF can be 'lone' but is frequently associated with underlying heart disease while in some patients a genetic cause has been identified. In the past decade our knowledge about the mechanisms of AF and our options for (non)pharmacological treatment of AF have increased importantly. Since the success rate of drug therapy is frequently disappointing "hybrid therapy" is often necessary (e.g., drugs in combination with cardioversion, pacemaker implantation or an ablation procedure). Therapy should focus on identifying the specific substrate (underlying heart disease) and triggers for AF in each patient, making a more individualized therapy possible. For this, non-invasive testing becomes more and more important. Holter recordings may show focal activity (monomorphic atrial premature beats, atrial tachycardia) or other supraventricular arrhythmias (AV-nodal reentrant tachycardia, circus movement tachycardia) which can successfully be treated. In addition, AF may transiently convert to atrial flutter (AFL), either spontaneously or after administration of (class IC) drugs. Recent studies have shown that ablation of the flutter circuit or ectopic activity can cure AF in many of these patients.

Anti-Arrhythmia Agents↗
PubMed2005

Persuasive writing in children, adolescents, and adults: a study of syntactic, semantic, and pragmatic development.

PURPOSE: Persuasive writing is a demanding task that requires the use of complex language to analyze, discuss, and resolve controversies in a way that is clear, convincing, and considerate of diverse points of view. This investigation examined selected aspects of later language development in the context of persuasive writing. The purpose of the study was to obtain current information that could be used to design collaborative instruction involving speech-language pathologists and classroom teachers. In schools today, these professionals often work closely together to facilitate students' language development, including their ability to write persuasively. METHOD: Persuasive writing was investigated in typically developing children, adolescents, and adults (N = 180) whose mean ages were 11, 17, and 24 years, respectively. Each participant wrote an essay on the controversial topic of animals being trained to perform in circuses. Following this, the essays were examined in detail, focusing on selected aspects of syntactic, semantic, and pragmatic development. RESULTS: Performance improved in each of these domains during the years between childhood and adulthood. Age-related changes included gradual increases in essay length; mean length of utterance; relative clause production; and the use of literate words, including adverbial conjuncts (e.g., typically, however, finally), abstract nouns (e.g., longevity, respect, kindness), and metalinguistic and metacognitive verbs (e.g., reflect, argue, disagree). In addition, older writers produced a greater number of different reasons in their essays and were more likely to acknowledge diverse points of view as compared to younger writers, thereby evidencing greater flexibility of thought. CLINICAL IMPLICATIONS: The study offers useful implications for speech-language pathologists and classroom teachers working together to improve students' persuasive writing skills. Suggestions are offered for ways to accomplish this by focusing on key aspects of later language development in the areas of syntax, semantics, and pragmatics.

Adolescent↗
PubMed2001

Efficacy of azimilide and dofetilide in the dog right atrial enlargement model of atrial flutter.

INTRODUCTION: Azimilide dihydrochloride blocks both the rapid (I(Kr)) and slow (I(Ks)) components of the delayed rectified K+ current; dofetilide blocks only I(Kr). Their efficacies were assessed on atrial flutter reentrant circuits in dogs with surgically induced right atrial enlargement. METHODS AND RESULTS: Multiple biopsies of the tricuspid valve and banding of the pulmonary artery in male mongrel dogs made them susceptible, about 3 weeks postoperatively, to stimulation-induced sustained (5 min or longer) atrial flutter. Azimilide 3 mg/kg administered intravenously (i.v.) terminated flutter in 8 of 8 dogs, but a slower, nonsustained arrhythmia could be reinduced in 5. In these 5 dogs, azimilide 10 mg/kg terminated flutter and prevented reinduction. This dose increased effective refractory period significantly more in the slow conduction zone (25%) than in the normal zone (17%) and increased flutter cycle length (37%). Termination followed progressive conduction delay in the slow zone of the reentrant circuit. Dofetilide 1 microg/kg i.v. terminated flutter in 6 of 6 dogs, but the arrhythmia could be reinduced. At 3 microg/kg, flutter terminated in all dogs and could not be reinduced. Dofetilide also increased the effective refractory period significantly more in the slow zone (17%) than in the normal zone (12%) and increased cycle length (33%), leading to interruption of the arrhythmia circuit. CONCLUSION: In the canine right atrial enlargement model of circus movement atrial flutter, both azimilide 10 mg/kg i.v. and dofetilide 3 microg/kg i.v. were 100% effective in terminating flutter and preventing reinduction. Efficacy relied on a similar mechanism of differentially prolonged refractoriness in the slow conduction component of the reentrant circuit where drug-induced termination occurred.

Animals↗
PubMed2003

Radiofrequency ablation of accessory pathways guided by the location of the ligament of Marshall.

INTRODUCTION: In humans, complex muscle connections are present near the junction between the coronary sinus (CS) and the ligament of Marshall. We hypothesize that these complex muscle connections participate in accessory pathway conduction. METHODS AND RESULTS: Electrophysiologic studies and radiofrequency ablation were performed in four patients with refractory AV reciprocating tachycardia. Case 1 was a 19-year-old male. Marshall bundle potentials were recorded by a catheter in the vein of Marshall. Radiofrequency energy application from that catheter resulted in successful ablation. Case 2 was a 43-year-old male who had undergone two unsuccessful radiofrequency ablation procedures of a left free-wall accessory pathway by conventional techniques. Coronary sinus electrography during tachycardia and ventricular pacing showed a long V-A interval. Radiofrequency energy application directed toward the ligament of Marshall eliminated the pathway conduction. Case 3 was a 17-year-old male who had undergone three unsuccessful ablation procedures. Radiofrequency energy application directed toward the stump of the vein of Marshall successfully eliminated the pathway conduction. Case 4 was a 20-year-old female who underwent one unsuccessful ablation procedure. Successful ablation was achieved in the left atrial free wall, approximately 1 cm above the AV annulus, at a location near the ligament of Marshall. CONCLUSION: We report four patients in whom successful accessory pathway ablation was achieved by targeting the ligament of Marshall. These findings suggest that the complex muscle connections among the coronary sinus, ligament of Marshall, and left atrium is important in accessory pathway conduction and maintenance of circus movement tachycardia in these patients.

Adolescent↗
PubMed2004

Automaticity in Mahaim fibers.

INTRODUCTION: Automatic rhythms associated with Mahaim fibers usually occur during radiofrequency catheter ablation. The incidence and significance of spontaneous automaticity in Mahaim fibers are unknown. METHODS AND RESULTS: Spontaneous automatic rhythms were observed in 5 (12.5%) of 40 patients with Mahaim fibers referred for nonpharmacologic therapy because of recurrent episodes of symptomatic tachyarrhythmias, usually antidromic circus movement tachycardia (33/40 patients). Three were female and two were male. Their mean age was 15 +/- 7 years compared to 26 +/- 13 years of the patients without automaticity (P = 0.09). Three patients had both antidromic tachycardia and asymptomatic spontaneous automatic rhythms recorded during ambulatory ECG (1 patient) or electrophysiologic study (2 patients). In 2 patients, the automatic rhythm triggered antidromic tachycardia. Two other patients had nonsustained repetitive episodes of wide QRS tachycardia due to automaticity arising in the Mahaim fiber, without antidromic tachycardia. All automatic rhythms were abolished by successful catheter ablation of the Mahaim fibers. CONCLUSION: Spontaneous automaticity occurred in 12.5% of our Mahaim patients and may trigger antidromic tachycardia. Spontaneous automaticity, which is not seen in rapidly conducting accessory pathways, is another argument for the presence of an AV nodal-like structure in Mahaim fibers.

Adolescent↗
PubMed2005

Short atrioventricular Mahaim fibers: observations on their clinical, electrocardiographic, and electrophysiologic profile.

UNLABELLED: Short A-V manheim fiber. INTRODUCTION: A short atrioventricular decrementally conducting accessory pathway is an uncommon variant of preexcitation. Available data from small series suggest that their decremental properties might not be caused by A-V nodal-like tissue. METHODS: We compared clinical, electrocardiographic and electrophysiologic parameters in two groups of patients: 8 patients with a short A-V Mahaim pathway (Group A), and 33 patients with atriofascicular pathways (Group B). Radiofrequency catheter ablation was carried out guided by activation mapping at the annulus in Group A patients and targeting the "M" potential in Group B patients. RESULTS: After ablation of all associated rapidly conducting bypass tracts, 7 of the 8 Group A patients showed clear preexcitation. In only 1 of 8 patients the short A-V Mahaim fiber was actively engaged in a reentrant tachycardia circuit. During radiofrequency catheter ablation an automatic rhythm occurred in 4 of 8 patients. Intravenous adenosine caused conduction a block in the Mahaim fiber in 3 of the 5 patients tested. In group B, no patient showed clear preexcitation (P<00001) while 72% had a minimal preexcitation pattern. Twenty-nine of the 33 patients had a circus movement tachycardia with AV conduction over the atriofascicular fiber. During radiofrequency catheter ablation 30 of 33 patients showed accessory pathway automaticity. Adenosine caused transient block at the atriofascicular pathway in 11 (92%) of the 12 patients tested. CONCLUSIONS: While short decrementally conducting right-sided accessory pathways show a typical ECG pattern different from atriofascicular pathways, their electrophysiologic properties do not seem to be uniform. Those pathways can be successfully interrupted by catheter ablation.

Adenosine Triphosphate↗
PubMed2000

Decremental conduction properties in overt and concealed atrioventricular accessory pathways.

AIM: Most atrioventricular accessory pathways (AV-APs) exhibit Kent bundle physiology characterized by fast and non-decremental conduction properties. In contrast, atriofascicular APs, which are only capable of reaching slow levels of long antegrade decremental conduction, are uncommon. The aim of this study was to describe antegrade and/or retrograde AV-APs with unusual decremental properties. METHODS AND RESULTS: Five patients with unusual decremental AV-APs underwent electrophysiological evaluation and radiofrequency catheter ablation for symptomatic tachycardias. Three were found to have structural heart disease, and three latent decremental AV-APs in the anterograde and/or retrograde direction that could not be demonstrated by routine electrophysiological testing. In Case 1, a right posteroseptal AV-AP with bidirectionally latent decremental conduction was associated with clinical antidromic circus movement tachycardia (CMT) mimicking ventricular tachycardia and orthodromic CMT, the latter inducible only with isoprenaline. In Case 2, incessant orthodromic CMT was due to a latent retrograde left posterolateral AV-AP. In both cases, double atrial responses to a single paced ventricular beat, initiating orthodromic CMT, were observed. In Case 3 with latent preexcitation unmasked by adenosine and atrial pacing, retrograde latent decremental conduction over a right posteroseptal AV-AP could be shown only with isoprenaline. This patient and the remaining two with overt preexcitation demonstrated anterograde decremental AP conduction that was discontinuous over a right posteroseptal AV-AP in Cases 3 and 4 and was continuous over a midseptal AV-AP in Case 5. In the latter case, the site of decremental conduction could be localized at the proximal AP origin. All five AV-APs were successfully ablated at the annulus level. CONCLUSION: AV-APs with unusual decremental properties that are either latent, demonstrable only during CMT or overt, exhibiting functional longitudinal dissociation are described. These APs could be identified and successfully ablated after detailed electrophysiological analysis.

Adenosine↗
PubMed1975

[Re-entry mechanism of ventricular tachycardias in the syndrome of nonhomogeneous delayed repolarisation (author's transl)].

The syndrome of Jervell and Lange-Nielsen with its characteristic combination of Q-T-(U) abnormalities and recurrent episodes of ventricular tachycardia (VT) or ventricular fibrillation can serve as a model for establishing recycling excitation (re-entry) as the likely cause of VT. The ECG abnormality in the Q-T-(U) segment indicates the underlying asynchronous repolarisation, probably localized in the His-Purkinje system. Asynchronous delayed repolarisation facilitates re-entry excitations. A personal case is reported which demonstrated two different patterns of inducing premature beats and VT, indicative of two different fascicular pathways of circus movement. The inducing extrasystole determines the circuit pathway and thus the ECG pattern of VT. The VT shows a fixed time relation depending on conduction delay and refractory period, which is a further indication for an underlying re-entry mechanism. Spontaneous changes in time relation or morphology point toward alterations in circuit pathways and can terminate the VT. Clinical findings in three further cases of the syndrome are reported. Furthermore, the possible general significance of these findings is highlighted by the occurrence of the described phenomena in seven patients in whom Q-T-(U) abnormalities exist merely as transient symptomatic disturbances.

Adult↗
PubMed1988

[Fetal atrial flutter in complete atrioventricular canal and trisomy 18].

Fetal supraventricular tachyarrhythmias are very rarely associated with congenital heart diseases. Usually a circus movement (= reentry), often associated with a preexcitation, and occasionally an atrial ectopic focus are suggested as the pathophysiologic mechanisms of supraventricular tachyarrhythmias. In the reported case - atrial flutter, complete common atrioventricular canal with fetal trisomy 18 - the atrial flutter was probably provoked by the dilatation of the atria due to the regurgitation of both atrioventricular valves. This case indicates the need for a detailed echocardiographic examination (using two-dimensional, M-mode, and Doppler-echocardiography) in each case of fetal tachyarrhythmias in order to exclude associated cardiac defects, possibly in association with a chromosomal anomaly.

Adult↗
PubMed2001

Conjoined twins, conception, pregnancy, and delivery: a reproductive history of the pygopagus Blazek sisters (1878-1922).

Conjoined twins represent the most uncommon twinning mechanism in humans, with an incidence approaching 1:100,000 deliveries. Although several conjoined male twins have occasionally been reported, for unexplained reasons most cases of conjoined twins are female. Of all the female conjoined twin sets either documented by medical authorities or referenced in ancient literary sources, in only one case were pregnancy and delivery successfully achieved by the conjoined twins themselves. We describe the highly unusual circumstance of the Blazek sisters, an extreme developmental example of the terminal monogenital pygopagus type of conjoined twins in which one of the joined sisters conceived and underwent labor and childbirth. Although little information is known about their own birth, these conjoined twins paradoxically hold a unique place in the history of obstetrics. Information from formal anatomic examinations of the sisters and their exploitative circus exhibitions is outlined with a view to explain relevant reproductive events. We present the sensational conception, pregnancy course, and subsequent vaginal delivery of a healthy male infant as summarized from contemporary sources. Additionally, the significance of pygopagus twins is discussed with regard to other types of monozygous twinning. Although modern operative techniques have been a welcome advance in the science of conjoined twin separation, the Blazek case is another reminder that, even in the era before complex surgery, conjoined twins were not necessarily consigned to an incomplete reproductive career.

Czechoslovakia↗
PubMed1985

Chorioptes bovis (Acarina: Psoroptidae) in some camelids from Dutch zoos.

The feet of three two-humped camels (Camelus bactrianus), one lama (Lama glama) and four alpacas (Lama pacos) from zoos and a circus in the Netherlands were examined for the mange-mite Choroptes bovis. Mites were found on two of the camels, the lama, and three of the alpacas. On one camel and one alpaca small mange lesions on the feet were present. This is the first report of Chorioptes bovis and chorioptic mange in the two-humped camel.

Animals↗
PubMed2007

Ethological study of manual laterality in naturalistic housed chimpanzees (Pan troglodytes) from the Mona Foundation Sanctuary (Girona, Spain).

During recent years, handedness of nonhuman primates has been the subject of several studies, especially focused on our closest relatives: the chimpanzees. These studies have dealt with both wild and captive chimpanzees, and they seem to point to divergent conclusions, which have been interpreted as a by-product of the human influence in the captive samples. Here we present the results of a study of 10 chimpanzees (Pan troglodytes). In the past, they were trained in circus and marketing tasks (humanised behaviours), until they were confiscated and accepted into the Mona Foundation (in northeast Spain) in 2000, where they live in a semi-naturalistic environment. This study has been performed through observational bouts without systematic human influence, recording the actions carried out by chimpanzees when performing spontaneous activities. Our results indicate that chimpanzees that were under strong human influence in the past show the same trend in handedness as those living in freedom: few significant lateralities were observed among either individuals or tasks. So, laterality may not be influenced by humanisation. However, this conclusion must be taken as preliminary because very few individuals were studied.

Animals↗
PubMed2005

Mold hysteria: origin of the hoax.

The topic of building related illness came into the public's eye as a major health issue in the mid 1970s, when several cases of pneumonia were found to be associated with an infectious agent in Philadelphia. This agent was subsequently found to be a gram-positive bacterium known as Legionella pneumoniae. During the ensuing 30 years, a myriad of symptom constellations, disorders, clinical syndromes and illnesses have been attributed to indoor living or working environments. Over time, there appeared to be no limit to claims of building related illness, and it was "reported" that almost any kind of clinical symptom, real or imaginary, could be blamed on indoor environments. As society became more and more litigious, many of these disorders were erroneously played out in courtrooms rather than medical offices, creating a circus atmosphere surrounding this class of disorders. With the advent of the internet, as well as other advances in telecommunications, these issues eventually became part of a media frenzy, and all truths could be thrown out the window as issues became more and more decided upon by emotions and unfounded beliefs, rather than scientific data and logical thinking.

Compensation and Redress↗
PubMed1995

New developments and treatment strategies in patients with supraventricular tachyarrhythmias.

The mechanisms, clinical presentation and therapy of supraventricular tachycardias are discussed. The therapy has changed from palliation by means of anti-arrhythmic drugs into definitive cure by ablation of the arrhythmia substrate. Radiofrequency energy causes tissue damage by heating and appears to be a safe method for catheter ablation of supraventricular tachycardias. We report a 97% success rate for radiofrequency ablation of 195 accessory atrioventricular pathways thereby curing these patients from circus-movement tachycardia and paroxysmal atrial fibrillation. Complications occurred in 3% of patients. One hundred seventy-two patients with atrioventricular nodal reentrant tachycardia, caused by reentry within dual AV-nodal pathways, were treated by selectively ablating one of the pathways with non-inducibility of the arrhythmia afterwards in 97% of the cases. Nine percent of patients had a recurrence but were successfully treated in a second session. The procedure was complicated by complete AV-block in 4% of patients. The disappointing medical treatment of atrial fibrillation and the fact that atrial fibrillation can be the cause of a reversible form of heart failure (tachycardiomyopathy), induced the clinical application of alternative forms of treatment. Ablation of the normal atrioventricular conduction system by using radiofrequency energy was performed with a 100% success rate in 121 patients. After implantation of a ventricular pacemaker it is possible to control and regulate the ventricular rhythm leading to rate control and amelioration of ventricular performance.

Atrial Fibrillation↗