bluuebunny/crossref_metadata_2025 huggingface dataset:
Propafenone: An Effective Agent for the Management of Supraventricular Arrhythmias
Authors: GRANT AUGUSTUS O.
Published: May 2007

Propafenone in SVT. Propafenone is a sodium channel blocking antiarrhythmic drug. It also has β‐adrenergic, potassium channel, and weak calcium channel blocking activity. The drug is metabolized in the liver with rates dependent on the debrisoquin phenotype. The saturable metabolism results in nonlinear pharmacokinetics. The metabolites retain sodium channel blocking activity but little β‐adrenergic blocking activity. Both controlled and noncontrolled studies have documented its efficacy in a variety of supraventricluar arrhythmias. Intravenous propafenone is effective in converting atrial fibrillation to normal sinus rhythm. Chronic oral administration decreases the frequency of recurrence of atrial fibrillation and paroxysmal supraventricular tachycardia. The drug is particularly effective in the Wolff‐Parkinson‐White syndrome. The drug may produce SA block in patients with underlying sinus node dysfunction. Propafenone has comparatively few noncardiac side effects. It is a useful primary drug or an alternative to more commonly used drugs used for the treatment of supraventricular arrhythmias.
Defibrillation Shocks Over Epicardial Patches Produce Sympathetic Neural Dysfunction in Man
Authors: RIGDEN LAWRENCE B. , MITRANI RAUL D. , WELLMAN HENRY N. , KLEIN LAWRENCE S. , MILES WILLIAM M. , ZIPES DOUGLAS P.
Published: May 2007

ICD Shocks Produce Sympathetic Neural Dysfunction. Introduction: The purpose of this study was to determine the effect of direct current (DC) shocks on cardiac sympathetic innervation in humans using I‐123‐metaiodobenzylguanidine (MIBG) sciutigraphy. Decreased efferent sympathetic neural function has been demonstrated following > 10‐J DC shocks delivered through epicardial patch electrodes in dogs. To evaluate the effect of DC shocks on cardiac sympathetic innervation in humans, we performed MIBG scintigraphy in 11 patients (ages 46 to 75 years) prior to and after receiving shocks from an implantable cardioverter defibrillator (ICD).

Methods and Results: This study was performed during an ICD generator change in 7 patients with epicardial patch electrodes and at the time of initial ICD implantation in 4 patients: 2 with epicardial patch electrodes, and 2 with a transvenous ICD system. All patients had spontaneous and inducible ventricular tachycardia. Prior to ICD implantation and remote from any cardioversions or shocks, baseline MIBG and thallium‐201 scintigraphy were performed. Repeat MIBG scintigraphy was performed after delivery of ICD shocks and compared with the baseline scans to determine the effect of the shock on sympathetic neural function. The baseline scans revealed focal areas of reduced MIBG uptake in areas of thallium perfusion defects in all patients except the patient without structural heart disease whose scans were normal. Postshock, patients with epicardial patch electrodes who received at least one 24‐J shock and had the postshock MIBG scan performed within 4 hours demonstrated no cardiac uptake of MIBG. Two patients with epicardial patch electrodes had no change in the postshock MIBG scans: I had a maximal shock of 20 J, and the other had the postshock scan delayed for 11 hours. The 2 patients with a transvenous lead system demonstrated no change in the postshock MIBG scan when compared with baseline.

Conclusions: This study demonstrates that following DC shocks delivered over epicardial patch electrodes, there is diffuse reduction in MIBG uptake that probably represents cardiac sympathetic neural dysfunction that appears to he transient. Sympathetic function does not appear to be affected by shocks delivered over a transvenous lead system.
Developmental Effects of d‐Sotalol on Anterograde and Retrograde Atrioventricular Conduction in the Rabbit
Authors: CASE CHRISTOPHER L. , LE FRANCIS K. , McKAY CHRISTINE A. , GILLETTE PAUL C. , HEWETT KENNETH W.
Published: May 2007

Developmental Electrophysiology of d‐Sotalol. Introduction: These experiments investigate the developmental effects of d‐sotalol on standard electrophysiologic parameters of anterograde and retrograde AV conduction in the rabbit.

Methods and Results: Using bipolar electrograms and standard pacing techniques, the effects of graded concentrations of d‐sotalol on anterograde and retrograde conduction in mature and immature perfused rabbit hearts were compared. Also, a quantitative assessment of the drug's effects on a rate‐dependent property of anterograde AV node (AVN) conduction, termed the “recovery process,” was compared in mature and immature rabbit hearts. The main developmental electrophysiologic findings of this investigation are: (1) in both the mature and immature rabbit heart, d‐sotalol increases the anterograde conduction time and prolongs refractoriness of the AVN, yet the minimal concentrations of d‐sotalol that produce these changes are lower in the neonate; (2) d‐sotalol increases the anterograde refractory period of the His‐Purkinje system in both age groups, but increases anterograde infra‐Hisian conduction only in the neonate; (3) 1 × 10−4 M d‐sotalol significantly changes the time constant of the AVN recovery process in the neonate, hut not in the adult; (4) for retrograde conduction, slow conduction through the AVN (HAmax) and infra‐Hisian region (VHmax) are increased by d‐sotalol in the neonate, but not in the adult.

Conclusions: The findings of this study illustrate that d‐sotalol has different effects on parameters of the developing AV conduction system. This implies that there may he maturational changes in the ionic currents that are responsible for anterograde and retrograde AVN and His‐Purkinje conduction.
Anisotropy, Fiber Curvature, and Bath Loading Effects on Activation in Thin and Thick Cardiac Tissue Preparations:
Authors: HENRIQUEZ CRAIG S. , MUZIKANT ADAM L. , SMOAK CHARLES K.
Published: May 2007

Anisotropy Effects in a 3D Bidomain. Introduction: A modeling study is presented to explore the effects of tissue conductivity, fiber orientation, and presence of an adjoining extracellular volume conductor on electrical conduction in cardiac muscle. Simulated results are compared with those of classical in vitro experiments on superfused thin layer preparations and on whole hearts.

Methods and Results: The tissue is modeled as a three‐dimensional bidomain block adjoining an isotropic bath. In the thin layer model, the fibers are assumed parallel. In the thick block model, fiber rotation, curvature, and tipping are incorporated. Results from the thin layer model explain experimental observations that the rate of rise of the entire action potential upstroke is faster and the magnitude of the extracellular potential is smaller across fibers than along fibers in a uniformly propagating front. The simulation identified that this behavior only arises in tissue with unequal anisotropy in the two spaces and adjoining an extracellular hath. Simulated conduction and potential distributions in the thick block model are shown to well approximate experimental maps. The potentials are sensitive to changes in the fiber orientations. A slight 5° tipping of intramural fibers out of the planes parallel to the epicardium and endocardium will lead to an asymmetry of the magnitudes of the positive regions. In addition, the introduction of fiber curvature leads to more realistic isochrone and extracellular potential distributions. The orientation of the central negative region of the extracellular potential is shown to be determined by the average of the fiber direction at the plane of pacing and the plane of recording.

Conclusions: The simulations demonstrate the sensitivity of spread of activation and potential time courses and distributions to the underlying electrical properties in both thick and thin slabs. The bidomain model is shown to be a useful representation of cardiac tissue for interpreting experimental data of activation.
The Mechanisms Responsible for Lack of Reproducible Induction of Atrioventricular Nodal Reentrant Tachycardia
Authors: ADA STRICKBERGER S. , DAOUD EMILE G. , NIEBAUER MARK J. , HASSE CAROL , MAN K. CHIN , MORADY FRED
Published: May 2007

Lack of AVNRT Induction. Introduction: AV nodal reentrant tachycardia (AVNRT) is not always reproducibly inducible. The purpose of this study was to determine the mechanisms responsible for the lack of reproducible induction of AVNRT.

Methods and Results: The induction of AVNRT was assessed with atrial burst pacing, and with atrial and ventricular programmed stimulation, each with one and two extrastimuli, in 103 patients with AVNRT. The stimulation protocol was repeated 10 times in the baseline state, during isoproterenol infusion, and after atropine administration, or until AVNRT was induced in 7 of 10 attempts. The mechanisms responsible for < 7 of 10 inductions were classified as: (1) the inability to achieve critical AH prolongation; (2) fast pathway block; and (3) slow pathway block. The induction endpoint was achieved in 90 patients: 55 in the baseline state, 34 during isoproterenol infusion, and 1 after atropine. Tbe mechanism of noninducibility in the baseline state (n = 48) was the inability to achieve a critical AH interval in 20%, fast pathway block in 49%, and slow pathway block in 31% (P = 0.02). During isoproterenol administration (n = 14) and after atropine administration (n = 13), the three mechanisms were equally responsible for nonreproducible induction of AVNRT.

Conclusions: The induction of AVNRT is poorly reproducible in approximately 10% of patients. In the baseline state, the most common reason for the inability to reproducibly induce AVNRT is fast pathway block. In the presence of isoproterenol or atropine, each of the three mechanisms was equally responsible for noninducibility of AVNRT.
Effect of Graded Increases in Parasympathetic Tone on Heart Rate Variability
Authors: GOLDBERGER JEFFREY J. , KIM YOU‐HO , AHMED MIRZA W. , KADISH ALAN H.
Published: May 2007

Parasympathetic Effects on Heart Rate Variability. Introduction: Time‐ and frequency‐domain measurements of heart rate variability have been used as indices of parasympathetic tone. However, studies of the effect of parasympathetic stimulation on these indices in humans have yielded conflicting results.

Methods and Results: This study evaluated the effects of parasympathetic stimulation on heart rate variability. Twelve normal subjects (7 males, 5 females; age 24.8 ± 3.4 years) were evaluated in the Clinical Research Center. Five‐minute ECG recordings were obtained at baseline and during graded phenylephrine infusions (0.3 and 0.6 μg/kg per min). Recordings were made during spontaneous respiration and when breathing was timed with a metronome at 15 cycles/min. Heart rate variability analysis was performed using standard time‐ and frequency‐domain parameters. Graded phenylephrine infusion resulted in a progressive increase in blood pressure and RR interval but no consistent changes in heart rate variability for the group. The results during normal versus metronome breathing were similar. Stepwise linear regression analysis revealed that the phenylephrine‐induced changes in heart rate variability were inversely correlated with the baseline heart rate variability and not related to the baseline KR interval or the phenylephrine‐induced change in RR interval.

Conclusion: These findings suggest that the respiratory variation in “parasympathetic effect” typically observed at the sinus node can be either increased or decreased by parasympathetic stimulation, depending on the initial level of parasympathetic tone and the intensity of stimulation. This resolves the previously conflicting data. Thus, evaluation of parasympathetic tone using heart rate variability techniques should be cautiously undertaken.
Pathological Findings Following Slow Pathway Ablation for AV Nodal Reentrant Tachycardia
Authors: OLGIN JEFFREY E. , URSELL PHILIP , KAO ANN K. , LESH MICHAEL D.
Published: May 2007

Pathology of Slow Pathway Ablation. Introduction: AV nodal reentrant tachycardia is routinely cured using radiofrequency catheter ablation techniques. However, there remains controversy as to whether the reentrant circuit for this tachycardia exists solely in the AV node or whether perinodal atrial tissues are vital to the circuit. In addition, the effects of radiofrequency ablation of the slow pathway of AV nodal reentrant tachycardia on the AV node are not known. We examined an autopsy specimen to determine the anatomical location and extent of AV nodal damage of radiofrequency slow pathway ablation for cure of AV nodal reentrant tachycardia.

Methods and Results: A 64‐year‐old woman with confirmed AV nodal reentrant tachycardia underwent a successful “slow pathway” AV modification with a single radiofrequency application. Five months after the procedure, the patient died from a spontaneous intracranial hemorrhage. Postmortem gross pathological examination of the heart was performed. The heart was then sectioned and stained for histologic examination. On gross examination, a pale lesion 0.5 cm in diameter was seen on the endocardial surface adjacent to the tricuspid annulus. approximately 0.85 cm anterior to the coronary sinus os and 1.15 cm from the apex of the triangle of Koch where the AV node resides. Histologic examination revealed a right atrial lesion composed of connective tissue and fat. The compact AV node and surrounding transitional cells were unaffected histologically, with normal atrial cells lying between the AV node and the lesion.

Conclusion: Ablation of the slow pathway to cure AV nodal reentrant tachycardia does not produce any gross or histologic damage to the AV node, suggesting that the AV nodal reentrant circuit does not exist in its entirety in the AV node.
Unusual Resetting Patterns in Response to Single Atrial Extrastimuli During AV Junctional Reentrant Tachycardia
Authors: TRITTO MASSIMO , CALABRESE PIETRO
Published: May 2007

Unusual Resetting Patterns in AV Junctional Reentry. Introduction: Two unusual resetting patterns were observed in two patients with slow‐fast AV junctional reentrant tachycardia (AVJRT) submitted to an electrophysiologic study.

Methods and Results: After AVJRT induction, resetting was evaluated by introducing single extrastimuli at progressively shorter coupling intervals from the high right atrium (HRA) and the proximal coronary sinus (CS). An alteration in the return cycle length duration allowed demonstration of resetting. In the first patient, during an AVJRT with a large excitable gap, properly timed extrastimuli delivered both from the HRA and CS simultaneously reset the tachycardia and advanced the H electrogram of the preceding tachycardia beat. In the second patient, both HRA and CS stimulation apparently failed to reset AVJRT (return cycle length unchanged), but, at critical coupling intervals, the cycle length duration of the tachycardia beat following the return cycle was consistently shortened.

Conclusions: During slow‐fast AVJRT, single atrial stimulation from sites remote to the reentrant circuit may result in unusual resetting patterns. Further studies are required to evidence the full spectrum of resetting in AVJRT.
Unequal Atrial Stretch in dogs Increases Dispersion of Refractoriness Conducive to developing Atrial Fibrillation
Authors: SATOH TAKASHI , ZIPES DOUGLAS P.
Published: May 2007

Atrial Stretch Precipitates Atrial Fibrillation. Introduction: We have shown previously that acute atrial dilation prolonged atrial refractoriness. We hypothesized that this increase in refractoriness might be heterogeneous and could create an electrophysiologic substrate leading to atrial fibrillation. The purpose of the present study was to test that hypothesis.

Methods and Results: We studied 23 anesthetized open chest dogs. Bipolar plunge electrodes were placed in the medial free wall of the right atrium (thin region) and in the lower crista terminalis of the right atrium (thick region). Two bipolar plunge electrodes were also placed in the left ventricular apex to stimulate and record. Atrial effective refractory period (ERP) was measured in a group of nine dogs using the atrial extrastimulus method (A1A2) in two ways: during atrial pacing (AP) and during simultaneous atrioventricular (AV) pacing that achieved an AV interval of 0 msec (AV = 0). One liter/hour of normal saline was infused intravenously to elevate right atrial pressure and produce right atrial stretch. Atrial ERPs were measured before and after the normal saline infusion. To compare the extent of atrial stretch produced by volume overload, two pairs of sonomicrometer transducers were implanted in the thick and thin regions in a separate group of six dogs. The area encompassed by sonomicrometers was measured before and after saline infusion. The inducibility of atrial fibrillation was compared before and after saline infusion using rapid AP in another group of five dogs. Atrial pressure during sinus rhythm increased from 5.1 ± 0.96 mmHg to 6.3 ± 0.93 mmHg after normal saline infusion (P < 0.01). ERP increased in the thin free wall from 151 ± 14.3 to 172 ± 14.7 msec (AV = 0), and from 149 ± 12.0 to 170 ± 14.3 msec (AP). ERP increased in the thick crista terminalis from 134 ± 9.9 to 147 ± 10.2 msec (AV = 0), and from 133 ± 7.9 to 146 ± 9.8 msec (AP) (P < 0.01). The increase in ERP in the thin free wall exceeded that in the thick crista terminalis (P < 0.01), increasing the dispersion of atrial ERP. After 500‐mL saline infusion for 30 minutes, the increase of area in the thin region was 12.8%± 3.7%, and that in the thick was 3.5%± 3.2%. The increase of the area in the thin region after 1000 mL for 1 hour was 18.8%± 6.2%. and that in the thick region was 6.3%± 5.1% (P < 0.01). Atrial fibrillation was not induced in any dog before saline infusion, hut induced in all five dogs after saline infusion.

Conclusions: Atrial ERP in the thin right atrial free wall exceeds the ERP of the thick cristaterminalis, and an increase in atrial pressure produced by saline infusion exaggerates this ditterence by stretching thin segments of the atrial myocardium more than it stretches thick regions. Thus, atrial stretch, by increasing the dispersion of atrial ERP, may be conducive to the development of atrial fibrillation.
Bi‐focal Atrial Tachycardia Mimicking Atrial Fibrillation: Fusion and Interference Between Two Distinct Tachycardias
Authors: EJIMA KOICHIRO , SHODA MORIO , TANIZAKI KOHEI , KASANUKI HIROSHI
Published: May 2007

Irregular tachycardias mimicking atrial fibrillation (AF) have previously been described. We report a case of a 60‐year‐old man with an antiarrhythmic drug‐resistant atrial tachycardia (AT) mimicking AF. The tachycardia consisted of two distinct ATs with interference of one repetitive AT with another sustained AT. Radiofrequency (RF) ablation of two distinct right atrial foci eliminated the irregular tachycardia. Although catheter‐based pulmonary vein isolation has become a popular therapeutic approach for patients with symptomatic AF, careful evaluation of the intracardiac recordings in the patients undergoing RF ablation for AF is important.
Right Ventricular Strain and Strain Rate Properties in Patients with Right Ventricular Myocardial Infarction
Authors: Sevimli Serdar , Gundogdu Fuat , Aksakal Enbiya , Arslan Sakir , Tas Hakan , Islamoglu Yahya , Buyukkaya Eyup , Gurlertop Hanefi Yekta , Senocak Huseyin
Published: May 2007

Background: This study was planned to assess strain and strain rate properties of right ventricle in patients with RV myocardial infarction. Material and Method: Thirty patients with acute inferior myocardial infarction were included in this study. The presence of right ventricular infarction in association with an inferior myocardial infarction was defined by an ST‐segment elevation 0.1 mV in lead V4 R. According to this definition, 15 patients had electrocardiographic signs of inferior myocardial infarction without right ventricular infarction (group I), and 15 patients had electrocardiographic signs of inferior myocardial infarction with right ventricular infarction (group II). Echocardiography was performed using a Vivid 5 System (GE Ultrasound; Horten, Norway) and a 2.5‐MHz transducer. 2‐dimensional color doppler myocardial imaging (CDMI) data for longitudinal function were recorded from the RV free wall using standard apical view. Offline analysis of the myocardial color Doppler data for regional velocity (V), strain rate (Sr), and strain (S) curves was performed using a special software program (EchoPac 6.4 Vingmed, Horten, Norway). They were assessed in basal, middle and apical segments of the RV. The differences between different groups were assessed with the Mann‐Whitney U‐test. A value of P < 0.05 was considered statistically significant. Results: Systolic tissue velocity, strain, strain rate of basal (4.8 ± 0.8 cm/s vs 6.5 ± 1.2 cm/s, −12 ± 3% vs −24 ± 5%, 1.28 ± 0.3/s vs −1.9 ± 0.4/s; P < 0.001, <0.001, <0.001, respectively) and mid (4.2 ± 0.5 cm/s vs 5.4 ± 0.5 cm/s, −16 ±3% vs −26 ± 4%, −1.2 ± 0.3/s vs −2.1 ± 0.3/s; P < 0.001, <0.001, <0.001, respectively) segments of right ventricle were significantly lower in patients with RV infarction than in patients without RV infarction. There were no differences between groups for apical strain, strain rate, and systolic tissue velocity. Conclusion: This study demonstrates that right ventricular strain and strain rate were lower in patients with left ventricular inferior wall myocardial infarction with, compared to without, right ventricular infarction.
Anomalies in Regeneration of Paramecium*
Authors: TARTAR VANCE
Published: May 2007

Using two different stocks of P. caudatum and four of P. multimicronucleatum it was observed (total of 25 cases) that starved fragments do not regenerate either end of the cell up to the time of death though they survived long past the time required by feeding fragments to regenerate. Fragments which were prevented from regenerating by an initial period of starvation later regenerated when supplied with nourishment (69 cases). Only three fragments failed to recover normal form when fed, two showing conspicuous abnormality instead and one remaining unable to feed. Short anterior fragments (32 cases) and posterior fragments (four cases) which are nucleate but do not include the feeding organelles can neither feed nor regenerate either normal body shape or the oral structures. In seven cases it was found that when the oral region of whole animals was injured they could no longer feed and in six of these cases no mouth or gullet could be found. It is therefore suggested that organelles of ingestion cannot be regenerated when excised or damaged even though the normal site be present. These observations are considered to demonstrate that regeneration in Paramecium is entirely different in type from that of most protozoa in that it occurs only through feeding and subsequent growth if ingestive organs are already present in part at least. It does not occur by the remodeling of body shape, with the formation of oral primordia derived from more general cytoplasmic differentiations, as is the case in most ciliates. The original surprise of Balbiani in finding that his fragments of Paramecium did not regenerate like other ciliates is now explained.
The Diatom Flora of Bethany Boǵ
Authors: PATRICK RUTH
Published: May 2007

The results of these studies indicate that the first diatom flora developed at the 13‐meter level. The flora at 12 meters increased. At the 11‐ and 9‐meter levels the lake became increasingly eutrophic. Both plankton and benthic forms were present. At the 8‐ and 7‐meter levels the lake was in a transitional stage from lake to bog conditions. From 6 meters to the surface bog conditions were present.
Autogamy in Paramecium polycaryum
Authors: DILLER WILLIAM F.
Published: May 2007

Mass cultures of a stock of Paramecium polycaryum maintained over a period of several years showed abundant and frequent nuclear reorganization stages resembling those of ex‐conjugant and ex‐autogamous animals of other species of Paramecium. Conjugation has never been reported for P. polycaryum, nor has it been found in these studies. Cytological examination of stained preparations revealed a process of autogamy in P. polycaryum, closely similar to that described previously for P. aurelia. As a rule, all four of the micronuclei, the typical vegetative number in P. polycaryum, engage in the first prezygotic division which is characterized by the formation of prophase crescents. Variable numbers of the eight nuclei continue with the second division. A maximum of sixteen nuclei may result. Apparently, only one of these normally completes the third prezygotic division to form the gametic nuclei, although more than one may initiate it. A fusion nucleus (synkaryon) arises in, or near, a paroral cone, thus paralleling autogamy in P. aurelia. A series of postzygotic divisions produces eight definitive nuclei, four of which become macronuclear anlagen and four remain micronuclei. The first division of the synkaryon results, possibly, in the formation of a viable nucleus and a non‐viable one, as in ex‐conjugants of P. caudatum. After the last micronuclear division, a skein evolves from the old macronucleus which has become flattened and leaf‐like. The skein rapidly segments into “sausages” which transform into spherical fragments, about thirty in number. Two cell divisions restore the normal vegetative nuclear complex.
Leucocytozoon in the Avian Order Columbiformes, with a Description of L. marchouxi Mathis and Leǵer 1910 from the Mourning Dove
Authors: LEVINE NORMAN D.
Published: May 2007

Leucocytozoon marchouxi is described from the mourning dove, Zenaidura macroura carolinensis in Illinois. The macrogametocytes are rounded or elliptical, measuring 7 to 11 by 8 to 15 microns (mean, 9 by 12 microns), and stain dark blue with Giemsa stain. The microgametocytes are often distorted or ruptured by the smearing process, but if not badly injured measure 5 to 11 by 8 to 15 microns, (mean, 8 by 11 microns). They stain pale blue with Giemsa stain. Host cell cytoplasm is rarely seen surrounding the microgametocytes, but was found in 26% of cells parasitized by the macrogametocytes. When present it forms a narrow border around part or all of the parasite's periphery, and is not drawn out to form elongate “horns.”

The parasite was found in ten birds, of which five were adults, one was a juvenile, and four were nestlings. The infections were relatively light in the adults. The youngest bird in which the protozoon was found was 14 days old.

The literature on Leucocytozoon in the avian order Columbiformes is reviewed. All forms with rounded gametocytes so far reported are considered to be L. marchouxi Mathis and Leger, 1910, of which L. turtur Covaleda Ortega and Gallego Berenguer, 1946, is considered a synonym.
The Opalinid Infusorians: Flagellates or Ciliates?
Authors: CORLISS JOHN O.
Published: May 2007

SUMMARY. The controversial question of the affinities of the enigmatic opalinids is discussed in the light of recent findings and with regard for modern ideas concerning characters of most significance in the phylogeny of various major protozoan groups. Metcalf's “protociliate” hypothesis still retains a high popularity although many of the factors supporting it have been adequately disproven during the past 20 years. The “ciliate‐” and “flagellate‐like” characteristics of the Opalinidae are listed and reviewed.

Considered to be one of the most significant of mastigophoran features is the “symmetrigenic” mode of fission, a character generally disregarded in the past. Coupled with nuclear monomorphism and a syngamous reproductive cycle the type of division presents a very strong argument in favor of closer affinities with the zooflagellates than with the ciliates. It is stressed that the opalinids are highly differentiated forms, not likely primitive or ancestral for any major group of protozoa, which have had a long evolutionary history of their own. Grassé's recent erection of a new super‐order in the Zoomastigophora to contain the family Opalinidae is defended and commended.
The Activity of Primaquine‐Pyrimethamine (Daraprim®) Combinations Against Plasmodium relictum in Pigeons
Authors: Parra Galo Soberon y , Reyes Rodolfo Perez
Published: May 2007

SUMMARY. As part of an extended series of experiments, various combinations of primaquine‐pyrimethamine were tested against pigeons infected with Plasmodium relictum.

(a) Rapid clearance of blood forms was observed, although each component had been reduced to one‐half of its previously established MED (minimal effective dose) for such clearance when administered alone.

(b) Primaquine‐pyrimethamine was followed by unprecedented delays in relapse after drug withdrawal. Such delays had not been elicited in any previous experiments in the series, employing each component alone, or chloroquine alone, or primaquine‐chloroquine combinations, or pamaquine‐plasmocid‐chloroquine (Premaline N).
A New Species of Actinomyxid Sporozoan Parasitic in a Fresh‐water Oligochaete.
Authors: NAIDU K. VANAMALA
Published: May 2007

SUMMARY. A new actinomyxid, Triactinomyxon naidanum, distinguished from other members of the genus by having 12 sporoplasms, is described from the intestine of an Indian fresh‐water oligochaete, Nais communis punjabensis. This is the first finding of an actinomyxid in Asia and also the first finding in a member of the family Naididae.
Protozoa of Amazonian and Andean Waters of Colombia, South America
Authors: Bovee Eugene C.
Published: May 2007

SUMMARY. A survey of protozoa in four water samples from Colombia, South America, yielded 84 species identifiable to genus or to species. Three of the collections were from the Amazon River and a tributary in the vicinity of Leticia, at the southern tip of the country. The fourth was taken near the high Andean town of Medellin in central Colombia.

All four subphyla are represented. Forty ciliophorans, 26 mastigophorans, 17‐sarcodinians, and one sporozoan are included. Of the ciliophorans all but one are euciliates in three orders. The exception is a suctorean. Two classes, and six orders of mastigophorans are represented; one class, and two orders of sarcodinians; and one class, one subclass, and one order of sporozoans. Eleven suborders, 33 families, and 49 genera are exemplified.

Other protozoa seen, but not identified to generic or specific accuracy, are omitted.
Volume Expansion of Euglena gracilis in Fresh Culture Media*
Authors: Corbett John J.
Published: May 2007

SUMMARY. Transfers of Euglena gracilis to fresh media gave rise to increased volumes of the flagellates, the magnitude of expansion varying with temperature, pH, osmotic pressure, and number of nutritional particles in the medium. Expansion was accompanied by decreased protoplasmic density and increased intracellular solids and water. When the population density of the flagellates was more than optimal, competition for substrates was reflected in reduced maximum volume. Below the optimal range, a similar decrease in maximum volume was observed.
A Species of Tetrahymena Parasitic in the Renal Organ of the Slug Deroceras reticulatum
Authors: Kozloff Eugene N.
Published: May 2007

SUMMARY. A ciliate found in the renal organ of the gray garden slug, Deroceras reticulatum, is referred to Tetrahymena (Paraglaucoma) rostrata (Kahl). In the parasitic phase, the ciliate is evidently not histiophagic. It is readily cultivated in bacterized tissue infusions, and has been established in axenic culture in yeast extract.

The number of complete primary ciliary meridians in ciliates of the parasitic phase has been observed to range from 41 to 58; in ciliates from cultures, the number of meridians has been observed to range from 28 to 37. In culture, the form of T. rostrata from D. reticulatum appears to be morphologically identical with a strain (NZ‐4) recovered from soil in New Zealand.
Replacement of Serum for In Vitro Cultivation of Tritrichomonas foetus*
Authors: Sanders Marvin
Published: May 2007

SUMMARY. The combination Tween 80 and cholesterol replaced blood serum as a requirement for the cultivation of Tritrichomonas foetus. Choline + potassium glycerophosphate enhanced growth in the presence of Tween 80 + cholesterol. A method for ensuring adequate cholesterol suspension‐an essential factor for consistent growth‐is described.
Euplotes leticiensis, n.sp., from the Letician Drainage into the Amazon River.*
Authors: Bovee Eugene C.
Published: May 2007

SUMMARY. In water taken March 3, 1956, from a tributary of the Amazon River, near Leticia, Colombia, an abundant ciliate fauna included large numbers of a species of Euplotes. Cursory examination showed a pronounced left wing like that of E. novemcarinatus Wang. Careful study, however, revealed a distribution of peristomal membranelles and peristomal morphology more like that of E. euryostomus Wrzesniowski. The positions of ventral cirri resemble those of E. woodruffi Gaw. The two right caudal cirri are furcated, as are those of the first two above‐mentioned species; but the five anal cirri are not. The C‐shaped macronucleus, like that of E. aediculatus Pierson, has the upper left part of the “C” somewhat depressed. A large organism, it averages 155 μ long by 130 μ broad, length ranging from 87 μ to 203 μ, and width from 67 μ to 194 μ. It is presented as Euplotes leticiensis n. sp.
Additional Observations on Gametogenesis and Fertilization in Trichonympha
Authors: Cleveland L. R.
Published: May 2007

SUMMARY. Some of the unusual types of sexual behavior in Trichonympha are considered: cytoplasmic incompatibility of gametes as shown in the fertilization process, pronuclear incompatibility, independence of pronuclear and cytoplasmic incompatibilities, loss of extranuclear organelles of male gamete, the formation of gametes with no chromosomes, those with the diploid number, and those with numbers between these extremes.
The Endogenous Development of Eimeria alabamensis Christensen, 1941, an Intranuclear Coccidium of Cattle
Authors: Davis Leonard Reid , Bowman George W. , Boughton Donald C.
Published: May 2007

SUMMARY. The endogenous development of the life cycle of Eimeria alabamensis Christensen, 1941, occurs in the nucleus of the intestinal cells of cattle. Calves were killed at various intervals after inoculation with infective oöcysts to study the endogenous cycle. Excysted sporozoites were found in the contents or scrapings from the walls of rumen, omasum, small intestine, cecum, and colon. They were found in the cytoplasm of intestinal epithelium at 2 days. Schizonts were found in the nuclei beginning at 2 days, but the number was low by the 8th day. Merozoite numbers usually ranged between 16 and 32. Some host nuclei contained as many as 48 or more, but these appeared to be the result of more than one schizont merging in the same host nucleus. Merozoites were slender, spindle‐shaped bodies while still in the schizont walls, but were short with bluntly rounded tips when found in intracellular spaces and crypts. Gametocytes were found as early as the 4th day. Most of the stages of gametogenesis were limited to the lowest third of the small intestine, but in heavy infections some were also found in the cecum and upper colon. Microgametocytes were multinucleate and were more densely stained than the uninucleate macrogametocytes. The ratio of macrogametocytes to microgametocytes in 100 gametes was 78: 22. Oöcysis with “shells” were found in sections of the lower 20 feet of the ileum on the 6th day, which coincided with the shortest prepatent period reported previously. As many as three schizonts or microgametocytes or four or five macrogametocytes or oöcysts could be found in the same host nucleus. The variations in shape of the oöcysts appeared to be dependent on the number of oöcysts crowded into each nucleus.
Types and Life Cycles of Centrioles of Flagellates
Authors: Cleveland L. R.
Published: May 2007

SUMMARY. Two centrioles, an old one and a new one, are always present in the resting cell. From prophase onward two new ones and two old ones are present. Beginning with the resting stage, five types of centriole life cycles are described and compared with one another: In type 1, both centrioles are elongate; in type 2, the old one is long and the new one, which is short, elongates in prophase; in type 3, both are short, both elongate in prophase, and both, except for their anterior tips, degenerate in late telophase; in type 4, both are long but in prophase their distal ends become free of the rest of the centrioles, these ends migrate to center or posterior end of cell, where, after they produce the achromatic figure and it completes its function in nuclear division, they degenerate; in type 5, both are short and neither elongates at any stage of its life cycle.

New centrioles are produced by the anterior ends of old ones. In their first generation, centrioles produce only extranuclear organelles (flagella, parabasals, axostyles, etc.); in their second and later generations, they produce only the achromatic figure (gametogenesis in Trichonympha and reorganization in Barbulanympha and Rhynchonympha are exceptions to this rule).

The distal ends of centrioles in some types of cycles are surrounded by centrosomes; in others they are not. In one type of centriole life cycle a small central spindle is present in the resting cell in two genera; in the other types this is not the case.
Relation between Multiplication Rate and Temperature in Tetrahymena pyriformis, Strains HS and GL
Authors: Prescott David M.
Published: May 2007

SUMMARY. The multiplication rate of Tetrahymena pyriformis HS in proteose peptone medium was measured at 12 temperatures between 18.4°C. and 36.6°C. At the temperature optimum, 32.5°C., the generation time is 2.25 hours. The upper lethal temperature lies between 36.6°C. and 38.0°C. Similarly, a study of Tetrahymena pyriformis GL revealed a temperature optimum for multiplication of 29°C. with a generation time of 3.70 hours. The upper lethal temperature falls between 34.6°C. and 35.4°C. At all temperatures employed the HS strain of organisms multiplies more rapidly than strain GL. Under identical conditions, the two strains have distinctly different growth optima, upper lethal temperatures and growth rates.

As measured by multiplication rate the readjustment to a sudden change in temperature (from 18.4°C. to 27.7°C.) is completed very rapidly, with an effective lag time of about 1 hour. Such a shift in temperature gives rise to a small degree of division synchrony during the first and second population doublings which follow. Subsequently, all traces of division synchrony are lost.
Growing Ochromonas malhamensis Above 35°C.*
Authors: Hutner S. H. , Baker Herman , Aaronson S. , Nathan Helene A. , Rodriguez Eugene , Lockwood Sally , Sanders Marvin , Petersen Robert A.
Published: May 2007

SUMMARY. Ochromonas malhamensis (Pringsheim strain) can be grown above 35.5°C.; below 35°, the previous chemically defined medium supports dense growth. The B12 and thiamine requirements rise steeply with temperature, and growth promotion by folic acid emerges; folic acid spares the enhanced B12 requirement. B12 is spared also, perhaps wholly bypassed, by purines + pyrimidines + amino acids (below 35°, exogenous purines, pyrimidines, and folic acid have little effect). Requirements also emerge for glycine (spared by serine), valine and isoleucine (their ratio is critical; leucine and threonine assist in maintaining a good balance), and, at very slightly higher temperatures, phenylalanine, tryptophan, cystine, and lysine. Requirements for Mg, Fe, Zn, and Mn appear to rise steeply with temperature; metal toxicities have to be circumvented carefully. The proportion of histidine + arginine to carbohydrate has to be increased, and a Krebs‐cycle component such as succinic acid becomes stimulatory. At 36.3–36.7°, a further supplement of crude natural materials such as an autoclaved suspension of Ochromonas cells is needed. Relevance of these findings to fever stress in vertebrates, general mitochondrial function, and repair of radiation damage, is discussed.
Genetic Studies of the Pyridoxine Mutant in Variety Two of Tetrahymena pyriformis*
Authors: ELLIOTT ALFRED M. , CLARK GORDON M.
Published: May 2007

SYNOPSIS. When two strains cf T. pyriformis that do not require exogenous pyridoxine are crossed, all progeny grow without the vitamin. Offspring from crosses of two pyridoxine requiring clones require pyridoxine with the exception of a few which will grow without pyridoxine. The ratio is approximately 3:1 favoring the pyridoxine requiring category. In matings involving the homozygous dominant pyridoxine requiring clones with the double recessive mutant, that is +/+ X p/p, all of the resulting progeny need pyridoxine. Test crossing these heterozygotes (+/p) with the parental pyridoxine non‐requiring clones (p/p) gives offspring approximating a 1:1 ratio. Matings between two heterozygotes derived from breeding experiments also yield progeny in approximately 3 pyridoxine requiring: 1 pyridoxine non‐requiring. All data indicate selection for the heterozygote in the population and a possible selection against either homozygote. The great abundance of heterozygotes and rarity of recessive homozygotes in natural habitats corroborates these findings. The genetic evidence supports a single gene hypothesis although the possibility of multiple closely linked genes cannot be ignored. There is also the possibility that a dominant suppressor gene may function in blocking the activity of the pyridoxine mutant genes. Moreover, if this gene exists it may be incompletely dominant since the heterozygote grows slightly on deficient media.
A Pheophytin‐like Pigment in Dark‐Adapted Euglena gracilis
Authors: GREENBLATT C. L. , SCHIFF J. A.
Published: May 2007

SYNOPSIS. The pigments of Euglena gracilis var. bacillaris change when cultures of light‐grown organisms are placed in the dark; the alterations in spectrum indicate the formation of a pheophytin‐like substance from chlorophyll. This pheophytin‐like compound is not an artifact of extraction and separation of the pigments; the spectral changes occur in the intact cells. The “dark” pigment is not yet definitely characterized. Formation of this material on dark adaptation seems dependent on the nutritional history of the cells.
Le Cortex de la Vacuole Contractile et son Ultrastructure chez les Ciliés
Authors: ROUILLER E. FAURÉ‐FREMIET et CH.
Published: May 2007

SYNOPSIS. In various ciliates the contractile vacuole is a permanent organelle, delimited by a differentiated cortex.

The cortex is made up of a dense reticulum of anastomosing tubules limited by a smooth membrane, and vesicles. This “spongiome” can be considered as a localized and specialized condensation of the endoplasmic reticulum.
Malayan Protozoa 1. Plistophora collessi n. sp. (Sporozoa:Microsporidia), an Ovarian Parasite of Singapore Mosquitoes*
Authors: LAIRD MARSHALL
Published: May 2007

SYNOPSIS. A brief introduction to a projected series of papers precedes the description of Plistophora collessi n.sp., parasitic in the egg follicles of Culex (Culex) tritaeniorhynchus Giles and C. (C.) gelidus Theobald. This microsporidian causes degeneration of the oöcyte, nurse cells and epithelium of the invaded follicle, within the distended limiting membrane of which a spherical cyst is formed. Such cysts measure from 45 to 340 μ (av., 220 μ) in diameter, and contain many sporonts. These average 50 μ in length and breadth and ultimately contain up to 300 (av., 200) sporoblasts, each of which develops into a single tiny (av., 2.5 by 1.4 μ) spore. Myriads of spores (many of them remaining grouped within the individual sporont membranes) pack the ripe cysts, which burst out into the lumen of the ovary in place of eggs, often associated in pairs, less commonly in groups of three, still enveloped by the follicular tube membrane. They roll about freely in the lateral and common oviducts, and are probably liberated, some of them eventually to be ingested by mosquito larvae, when the infected females attempt to oviposit.
Susceptibility and Resistance of Avian and Mosquito Hosts to Strains of Plasmodium relictum Isolated from Pigeons*
Authors: HUFF CLAY G. , MARCHBANK DOROTHY F. , SHIROISHI TSUGIYE
Published: May 2007

SYNOPSIS. Two strains (1B and 1P) of Plasmodium relictum isolated from pigeons could be easily passed serially in pigeons by transfer of infected blood. What appeared at first to be a qualitative difference between the infectiousness of gametocytes of strain 1P in pigeons and of gametocytes of the strain after being adapted to canaries (1P1) was found to be only a quantitative difference in their infectivity for mosquitoes. Earlier work had indicated that gametocytes of strain 1P were noninfectious for mosquitoes. The experiments reported here show that Culex tarsalis is highly susceptible to gametocytes of both strains 1B and1P and that Culex pipiens is slightly susceptible to gametocytes of strain 1P.

The susceptibility of 72 pigeons (belonging to 24 varieties, plus mongrels and 3 species hybrids) to sporozoites of strain 1P1 was tested; only 5 transient infections lasting no more than two days and 3 subpatent infections were obtained. Similar results were obtained with sporozoites of strain 1B.

The two strains are similar in both mosquito and avian hosts except that 1B is more highly infectious for C. pipiens and C. tarsalis than 1P. There is evidence that one or both of these strains may be Plasmodium relictum matutinum, Huff(7). A proposed hypothesis indicates that (1) various species of mosquitoes have different susceptibilities, (2) various species of avian hosts are infectious to different degrees, and (3) that the probability of a mosquito of a given species being infected from a given species of parasite may be expressed by the degree of overlap between the normal curves of susceptibility of the mosquito and infectiousness of the gametocytes in the pertinent avian host. The susceptibilities of pigeons to sporozoites of the two strains of parasites and of mosquitoes to gametocytes produced in pigeons are so low that it can be questioned whether these strains could persist in nature without the presence of other avian hosts on the one hand possessing greater susceptibility than the pigeon to sporozoites and on the other hand contributing more to the infectiousness of the gametocytes than the pigeon does.
Resistance of Calves to Reinfection with Eimeria bovis
Authors: SENGER CLYDE M. , HAMMOND DATUS M. , THORNE JOSEPH L. , JOHNSON A. EARL , WELLS G. MARK
Published: May 2007

SYNOPSIS. An immunity to reinfection with E. bovis was demonstrated in 3 experiments involving 60 calves. This immunity develops rapidly, as indicated by resistance to a challenge given 14 days after the immunizing inoculation. In 3 groups of 3 to 6 young calves each, immunity was still present to a moderate degree 2 to 3 months after inoculation; in one group of 5 animals about a year old there was apparently a high degree of immunity about 7 months after the last inoculation. In one experiment an immunizing inoculum of 10,000 oöcysts did not produce as much immunity as 50,000 oöcysts. In 2 experiments there appeared to be little difference in the immunity produced by a single inoculation of 50,000 as compared with 100,000 oöcysts, but inoculation with 100,000 oöcysts, resulted in substantially longer and more severe illness than 50,000 oöcysts. There appeared to be no appreciable difference in clinical symptoms or development of immunity between calves given a single immunizing inoculum and those given the same number of oöcysts in 5 equal inocula on successive days. Treatment with sulfamethazine and sulfamerazine (Merameth) 13 to 15 days after inoculation alleviated the clinical symptoms of coccidiosis without interfering appreciably with the development of immunity. In one experiment with 7 calves, no beneficial effect was noted from 1 or 2 transfusions of 500 ml. of plasma and leucocytes from immune calves into 4 calves 1 and 12 days or 11 days after a challenge inoculation.