Atypical Form of the Fourth Criterion for Transient Entrainment

The typical fourth criterion for transient entrainment is defined when both a sudden shortening in conduction interval to and a distinct change in electrogram morphology at a bipolar recording site are demonstrated while performing overdrive pacing of a reentrant tachycardia from a single pacing site at two different constant rates. The purpose of this article was to test the hypothesis that if an intracardiac recording site showing both orthodromic and antidromic capture with entrainment pacing is located suitably distant from the circuit, sudden shortening in conduction interval to that site may occur without any significant change in the bipolar electrogram morphology (i.e., atypical form of the fourth criterion). Atrial overdrive pacing of orthodromic tachycardia was performed in 20 patients with either left anterior (12 patients) or left posterior (8 patients) accessory pathways. We investigated the effects of overdrive pacing from the proximal or distal coronary sinus, specifically effects on the electrogram interval and the electrogram morphology at the right atrial appendage. Overdrive pacing of orthodromic tachycardia from the proximal coronary sinus was performed in 10 of the 12 patients with left anterior accessory pathways; those 10 patients demonstrated the first entrainment criterion at the right atrial appendage site. Overdrive pacing of orthodromic tachycardia at still shorter cycle lengths demonstrated a sudden shortening in conduction interval to the right atrial appendage site. Despite shortening in conduction interval the morphology of the right atrial appendage electrogram was completely or almost identical to that during orthodromic tachycardia, indicating an atypical form of the fourth criterion. This criterion was not demonstrated in patients with left posterior accessory pathways. Thus, atypical fourth entrainment criterion was demonstrated during overdrive pacing of orthodromic tachycardia from the proximal coronary sinus only in patients with left anterior accessory path ways. Demonstration of atypical fourth criterion seems largely dependent on the location of the accessory pathway, the pacing, and the recording sites.     

Protecting spermatogonia from apoptosis induced by doxorubicin using the luteinizing hormone-releasing hormone analog leuprorelin

PURPOSE: The present study was performed to investigate the protective effect of leuprorelin (LH-RH analog), on spermatogonia apoptosis induced by doxorubicin (DXR) in the Sprague-Dawley rat model. METHODS: Twenty-four adult male rats were divided into the following four groups: (i) control group; (ii) group given doxorubicin (intravenous injection, 8 mg/kg); (iii) group given leuprorelin (subcutaneous injection, 3 mg/kg); and (iv) group given both doxorubicin (intravenous injection, 8 mg/kg) and leuprorelin (subcutaneous injection, 3 mg/kg). Evaluation for quantification of apoptotic spermatogonia was made by the ratio of TUNEL-labeled spermatogonia versus 100 Sertoli cells in each seminiferous tubule. Two hundred seminiferous tubules of each rat were assessed. RESULTS: The ratio of apoptotic spermatogonia versus 100 Sertoli cells at stages II-IV of the groups given DXR (groups 2 and 4) were significantly higher than those of the other groups. However, the value at stages II-IV of the group given both DXR and leuprorelin (group 4) was significantly lower than that of the group given DXR (group 2). CONCLUSION: The significant prophylactic effect (P < 0.05) of LH-RH analog against doxorubicin-induced spermatogonial apoptosis was observed in a stage specific manner by microscopic evaluation with TUNEL.     

Clinical features of childhood-onset schizophrenia with obsessive-compulsive symptoms during the prodromal phase

Abstract Thirty-nine patients with schizophrenia, diagnosed according to DSM-III-R, who were under 15 years of age, were studied in two groups; 16 subjects with obsessive-compulsive symptoms during the prodromal phase, and 23 with no obsessive-compulsive disorders. The group with obsessive-compulsive symptoms during the prodromal phase was characterized by a higher ratio of males, higher incidences of perinatal and brain computed tomography (CT) abnormalities, fewer hereditary factors, longer duration of the prodromal phase, and a higher incidence of insidious onset and negative symptoms compared with the group without such prodromal symptoms. Schizophrenic patients with obsessive-compulsive symptoms during the prodromal phase were clinically distinct from those without, which suggests the possibility of subtype categorization.     

Demonstration of Right and Left Atrial Dissociation by Atrial Rapid Pacing or Extrastimulation During Fast-Slow (Uncommon) Form of Atrioventricular Nodal Reentrant Tachycardia

Some recent works suggest that extranodal atrial fibers may form part of the reenlry circuit in the atrioventricular (AV) nodal reentrant tachycardia (AVNRT). This hypothesis is based on the fact that the perinodal dissection successfully abolished AVNRT while preserving intact AV conduction. Apart from the surgical success, the electrophysiological evidence supporting this hypothesis has not been demonstrated, especially in the uncommon (fast-slow) form of AVNRT. We present some electrophysiological evidence suggesting atrial participation in eight patients with the fast-slow form of AVNRT. During the tachycardia, rapid pacing or extrastimulation was done from the orifice of the coronary sinus (CS) and the right atrium (RA), while recording the electrograms of the CS and the low septal RA. In seven patients, right and left atrial dissociation was demonstrated during pacing from the RA, while in the remaining one this was demonstrated from the CS. The interatrial dissociation will be unlikely if the intranodal reentry circuit connects with the atria via a single upper common pathway. This suggests that the upper turnaround of the reentry circuit involves atrial tissue and that the extranodal accessory pathway with long conduction times may form the ascending limb of the circuit (atrionodal reentry). Alternatively, the reentry circuit is entirely intranodal and two or more connecting pathways are present between the atria and the circuit.     

Relationship between cellular ATP content and cellular functions of primary cultured rat hepatocytes in hypoxia

The importance of oxygen in maintaining the functional integrity of hepatocytes has been well established in a variety of experimental models, such as in vivo , perfused liver and isolated hepatocytes. However, one of the shortcomings of these systems is their short life span. Therefore, we have examined the effects of long-term hypoxia on cellular adenine nucleotide content and cellular functions, such as albumin production, urea production and DNA synthesis, in adult rat hepatocytes in primary culture. Hepatocytes were cultured at a density of 11 × 10⁴ and 5 × 10⁴ cells/0.18 mL per cm² for the study of albumin and urea production and DNA synthesis, respectively, at various oxygen tensions (20, 12, 8 and 5%) for 24 h. Cellular ATP content in cultured hepatocytes in hypoxia gradually declined, corresponding to the decrease in oxygen tension, and the cellular ATP level at 5% oxygen was approximately 20% of that at 20% oxygen. Albumin production also decreased in parallel with the decrease in cellular ATP content in cultured hepatocytes in hypoxia. However, even when cellular ATP content gradually declined corresponding with the decrease in oxygen tension in cultured hepatocytes in hypoxia, such as at 8 or 5% oxygen, urea production remained at a high level; in contrast, DNA synthesis was completely suppressed. These results suggest that the cellular ATP content decreases in cultured hepatocytes during long-term hypoxia in relation to oxygen tension and that the relationship between decreased ATP levels and liver function in cultured hepatocytes during hypoxia differs for albumin production, urea production and DNA synthesis.     

Pharmacokinetic Analysis of Increased Toxicity of 2-sec-Butylphenyl Methylcarbamate (BPMC) by Fenitrothion Pretreatment in Mice

Pharmacokinetk Analysis of Increased Toxicity of 2-sec-ButylphenylMethylcarbamate (BPMC) by Fenitrothion Pretreatment in Mice.TSUDA, S., MIYAOKA, T., IWASAKI, M., AND SHIRASU, Y. (1984).Fundam. Appl. Toxicol. 4, 724–730. The potentiating effectof O,O-dimethyl O-(3-methyl-4-nitrophenyl) phosphorothioate(fenitrothion) on the toxicity of 2-sec-butylphenyl methylcarbamate(BPMC) in male mice was analyzed pharmacokinetically. The animalspretreated by dietary administration of 1000 ppm fenitrothionfor 1 week (4.4% of the po LD50 daily) did not show toxic symptomsexcept for a slight decrease in body weight In the fenitrothion-pretreatedmice, toxicity of fenitrothion was not changed but a fivefoldpotentiation was observed in po and ip acute lethality and athreefold potentiation of iv lethality of BPMC. Toxic signsafter BPMC administration were similar regardless of fenitrothionpretreatment or of route of administration. Fenitrothion pretreatmentfollowed by BPMC administration (20 mg/kg po or 8 mg/kg iv,approximate LD5 in the pretreated mice) significantly increasedthe plasma BPMC concentration and the total area under the plasmaconcentration versus time curve (AUG_0-. The pretreatment increasedthe oral AUC_0-, more greatly than the iv AUC_0-, (for po, 6.3-fold;for iv, 2.0-fold). The oral systemic availability of BPMC (fractionreaching systemic circulation) was increased by fenitrothiontreatment to 3.3-fold. These results suggest that a major causeof the potentiation may be the increase in amount of BPMC inthe systemic circulation.     

Differences in the Mode of Lethality Produced through Intravenous and Oral Administration of Organophosphorus Insecticides in Rats

Differences in the Mode of Lethality Produced through Intravenousand Oral Administration of Organophosphorus Insecticides inRats. TAKAHASHI, H., KOJIMA, T., IKEDA, T., TSUDA, S. and SHIRASU,Y. (1991). Fundam. Appl. Toxicol. 16, 459–468. This studywas undertaken to investigate the possibility that mechanismsother than cholinesterase (ChE) inhibition account for the acutetoxicity of organophosphorus insecticide. Both the PO type insecticide(direct ChE inhibitors: chlorfenvinphos and dichlorvos) andthe PS type insecticide (indirect ChE inhibitors: diazinon andfenthion) were employed. Rats treated with lethal doses of intravenousand oral PO type insecticides and oral PS type insecticidesexhibited typical signs of anti-ChE poisoning along with markedinhibition of brain and erythrocyte ChE activity. In contrast,rats given lethal doses of intravenous PS type insecticidesexhibited tonic convulsions and opisthotonos, with only slightinhibition of ChE activities. When PO type insecticides wereintravenously administered to anesthetized and conscious rats,animals exhibited typical anti-ChE poisoning signs in cardiorespiration:hypertension and apnea which were antagonized by atropine. Afteradministration of lethal doses of PO type insecticides, breathingdisappeared before the cessation of heart beats. Rats receivinglethal doses of intravenous PS type insecticides did not showhypertension, but exhibited transient cessation of breathingand heart beats. Breathing was observed after the disappearanceof heart beats. The electroencephalogram (EEG) was characterizedby spike and wave complexes. The EEG and cardiorespiratory changeswere not antagonized by atropine. It was concluded that lethalityfollowing intravenous PS type insecticides may be independentof ChE inhibition.     

PLENARY LECTURES-PL1 Toxicity of perfluorooctane sulfonate and perfluorooctanoate

Persistent perfluorinated organic compounds, such as perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are used in a variety of industrial applications. They are very stable in the environment, distribute widely in the global environment and in wild life, and are detected in human sera.     

New Diagnostic Finding to Assess Para-Hisian Pacing Observed in a Patient with a Permanent Form of Junctional Reciprocating Tachycardia

Morphologic Change During Para-Hisian Pacing. Para-Hisian pacing, a useful method to differentiate conduction over an accessory pathway from conduction over the AV node, is assessed essentially by comparing the timing of local atrial electrograms between Hisbundle captured heats and His-bundle noncaptured heats. We describe the case of a patient with a permanent form of junctional reciprocating tachycardia, in whom an atrial double potential was recorded only during the tachycardia at the right posterior septum. During para-Hisian pacing, a morphologic change in the atrial electrogram at the posterior septum was also identified, as well as a change in the retrograde atrial sequence. Since the morphologic change of atrial electrograms during para-Hisian pacing cannot be demonstrated in a patient without an accessory pathway, this new finding could he considered a new additional diagnostic criterion suggesting the presence of an accessory pathway.