Viscoelastic properties of tissue conditioners — stress relaxation test using Maxwell model analogy

In order to measure the viscoelastic properties of tissue conditioners, a series of stress relaxation tests was carried out using poly ethyl methacrylate polymer powders and liquids composed of butyl phthalyl butyl glycolate/ethyl alcohol mixtures, respectively. The analysis method using the Maxwell model analogy is discussed. The results may be summarized as follows. (i) In this study it was feasible to make the stress relaxation curves for 30 min analogous to the Maxwell model, using a model with a maximum of 5 elements. (ii) The elastic modulus Ei, the coefficient of viscosity eta i, and relaxation time tau i, for each element, and the instantaneous modulus E0, tended to increase with time. These values in the element of the longest relaxation time were most marked in the increase among those in all the elements. Furthermore, in every element the rate of increase of eta i was greater than that of Ei. The method described is considered to be one of the most useful techniques available for the study of the viscoelastic properties of tissue conditioners.     

Differential Effects of Dopamine Antagonists on Evoked Dopamine Release from Slices of Striatum and Nucleus Accumbens in Rats

The effects of dopamine-receptor antagonists on electrically-evoked dopamine release were compared in the nucleus accumbens and striatal slices of rats. (-)-Sulpiride induced a concentration-dependent increase in the evoked dopamine release from both regions, the increase in the nucleus accumbens being significantly greater than that in the striatum. Clozapine also increased evoked dopamine release from the nucleus accumbens, but not from the striatum. The haloperidol-induced increase in evoked dopamine release from the nucleus accumbens was less than that from the striatum. These findings indicate that, in terms of dopamine transmission, (-)-sulpiride and clozapine, but not haloperidol, predominantly affect the nucleus accumbens rather than the striatum. We have previously reported that the contribution of D₃ receptors to the regulation of dopamine release from dopamine nerve terminals is much greater in the nucleus accumbens than that in the striatum. (-)-Sulpiride and clozapine have relatively higher affinity for D₃ receptors than does haloperidol. The regional differences in responsiveness of dopamine release to dopamine antagonists could be due to the different affinities to D₂ or D₃ receptors of the dopamine antagonists.     

Post‐stroke depression and apathy: Interactions between functional recovery,lesion location,and emotional response

Depression and apathy are often observed after stroke and are often confused with one another. In the present review, we argue that the current concept of ‘post‐stroke depression’ (PSD) in fact consists of two core symptoms or syndromes: (i) affective (depressive) PSD; and (ii) apathetic PSD. We argue that these two core symptoms are each associated with a different underlying neuroanatomical mechanism, a pattern that influences functional recovery. Post‐stroke disabilities can provoke several distinct emotional responses, some of which are associated with severe depression. We examined one of these emotional responses previously, namely ‘insistence on recovery’, which was believed to be a negative indicator of functional improvement in disabled stroke patients. However, an appropriate level of insistence on recovery may, in fact, be associated with reduced depression and apathy, resulting in enhanced recovery from stroke‐related disabilities. Improvements in physical disabilities (trunk stability or activities of daily living, such as walking) also reduce depression and apathy. Therefore, the experience of PSD/apathy may be intertwined with various initial emotional responses and improvements in physical functioning. Effective treatment of PSD/apathy requires a multidisciplinary approach, such that neuroanatomical/neurobiological, emotional, and physical (rehabilitation) domains are all addressed.     

A flow cytometric method for measurement of hydrogen peroxide generation by pediatric polymorphonuclear leukocytes stimulated by Staphylococcus aureus and Escherichia coli

The generation of hydrogen peroxide (H₂O₂), one of the reactive oxygen species, by polymorphonuclear leukocytes (PMN) stimulated by Staphylococcus aureus and Escherichia coli was studied in infants by cytofluorography. After heparhized whole blood was incubated with bacteria for 60 min, generated H₂O₂ was measured. The positive rate of H₂O₂ generation of PMN and mean fluorescent intensity of positive PMN stimulated by S. aureus and E. coli were significantly reduced in infants aged < 1 year and H₂O₂ generation increased with advancing age. In 10–15 year old children, the level of generated H₂O₂ reached adult levels. When sera from 1 year old children were added to separated PMN from healthy adults, H₂O₂ generation was reduced. In contrast, H₂O₂ generation by PMN from 1 year old children was increased by the addition of adult sera. These results suggest that the ability to generate H₂O₂ in response to S. aureus and E. coli is lower in infants and that such reduced activity may be related to the susceptibility of such infants to S. aureus and E. coli infections.     

Viscoelastic properties of tissue conditioners — influence of ethyl alcohol content and type of plasticizer

The effect of both the ethyl alcohol content of liquids and the type of plasticizer on the viscoelastic properties after gelation of tissue conditioners was studied by means of a stress relaxation test. The results are summarized as follows. The liquids containing the larger percentages of ethyl alcohol produced the larger flow after gelation. Furthermore, the ethyl alcohol content had a significant influence on changes in viscoelastic properties with the passage of time. Flow properties were found to reduce rapidly with time of storage with an increase in the ethyl alcohol content. The use of benzyl benzoate produced the larger flow after gelation than dibutyl phthalate, which in turn produced the larger flow than butyl phthalyl butyl glycolate. The type of plasticizer, however, was found to have no influence on changes in viscoelastic properties with the passage of time.     

Multiple Endocrine Neoplasia Type 2b (I) Report of a Case

This is a case report of a 14-year-old girl with multiple endocrineneoplasia (MEN) type 2b. The patient had mucosal neuromas, medullarycarcinoma of the thyroid, bumpy lips, hypertrophied cornealnerves, absent flare response following intradermal histamineinjection, high arched palate, oligodontia, pes cavus and polypoidlesions in the colon. Urinary catecholamines were normal andthe patient's blood pressure did not rise abnormally after glucagonor histamine infusions. The left adrenal gland was not visualizedon examination by adrenal scintiscanning, but by computed tomographyit was enlarged. Nerve growth factor (NGF) was normal in theserum. Extensive studies failed to identify other family memberswith MEN. This patient seems to be a sporadic case.     

Unidirectional Atrio-Atrial Conduction after Surgical Isolation of the Posterior Part of the Left Atrium and Pulmonary Veins for Atrial Fibrillation:

A 66-year-old woman underwent mitral valve replacement and surgical isolation of the posterior part of the left atrium for persistent AF. During sinus rhythm an isolated atrial rhythm was recorded from the isolated posterior left atrium using an esophageal electrode catheter. After the intravenous administration of adenosine triphosphate sinus rhythm was suppressed and 1:1 conduction from the posterior left atrium to the rest of the atrium was recorded. Unidirectional atrio-atrial conduction was revealed by a simple electrophysiological evaluation.(PACE 2004; 27[Pt. I]:812–814)     

Ablation of Idiopathic Ventricular Tachycardia in Two Separate Regions of the Outflow Tract: Prevalence and Electrocardiographic Characteristics

Few studies have clarified the prevalence and characteristics of idiopathic outflow tachycardia (OT-VT) with an altered QRS morphology after radiofrequency catheter ablation (RFCA), requiring additional RFCA applications at a different portion of the outflow tract (OT) to abolish the OT-VT. Among 344 patients (97 VTs and 247 premature ventricular contractions), 12 (3.5%; VTs-7, PVCs-5; 6 women) had dynamic QRS morphology changes following the RFCA, requiring additional RFCA applications at a different portion to abolish the OT-VT. In 8 of 12 patients (67%), this phenomenon occurred following RFCA at right (RVOT; n = 7) or left ventricular (LVOT; n = 1) endocardial sites of the OT: The second OT-VT was consistently associated with an increase in the R-wave amplitude in the inferior leads, and in five it was finally abolished by RFCA at the left sinus of Valsalva (LSV). Conversely, in four patients (33%), the second OT-VT appeared after RFCA at the LSV: two required additional RFCA applications at the LVOT to abolish the second OT-VT, and one at the RVOT, and all were associated with a decrease in the R-wave amplitude in the inferior leads. This kind of dynamic QRS morphology change was often observed when RFCA was applied to either the first or second OT-VT at a right or left ventricular endocardial site, with the other site being the LSV. A detailed continuous observation of the QRS morphology, especially of the R-wave in the inferior leads, is important for identifying changes in the QRS morphology during RFCA .     

Prevalence and Characteristics of Left Atrial Tachycardia Following Left Atrial Catheter Ablation

Background: Left atrial tachycardia (AT) is a complication of left atrial catheter ablation (LACA) of atrial fibrillation (AF). However, its prevalence and characteristics have not been sufficiently clarified.
Methods: We divided 121 patients who underwent LACA into 2 groups based on the results of AT occurrence after LACA (follow-up period; 12 ± 7 months): an AT+ group and AT– group.
Results: New-onset left AT occurred in 30 patients (25%) 31 ± 51 days after LACA. Among the 26 patients with an early onset of AT, 4 underwent a second ablation for AT, and 21 became free of AT within 6 months without a repeat ablation procedure. Among the 4 patients with a late onset of AT (>2 months after the LACA), the tachycardia remitted without a repeat ablation procedure in a single patient within 6 months. Among 71 patients who underwent LACA with additional ablation lines, 22 (31%) developed new-onset left AT. Among 50 patients who underwent LACA alone, 8 (16%) developed new-onset left AT (P = 0.02).
Conclusions: New-onset left AT is a frequent complication of LACA for AF, especially in men and in patients with a low left ventricular ejection fraction. Early (<2 months) onset AT does not require a repeat ablation because it often represents a transient phenomenon and disappears spontaneously.     

Maximum Ventricular Dyssynchrony Predicts Clinical Improvement and Reverse Remodeling during Cardiac Resynchronization Therapy

Background: Tissue synchronization imaging (TSI) and tissue tracking imaging (TTI) might facilitate the evaluation of ventricular dyssynchrony.
Methods: In 22 patients, TSI and TTI were performed before and <1 month after onset of cardiac resynchronization therapy (CRT). With TSI guidance, maximum left ventricular (LV) intraventricular conduction delay (IVCDmax) was the greatest difference in time-to-peak velocity between septum and lateral wall. IVCD between the basal septum and lateral wall (IVCDbase) was also measured. Using TTI, the mean peak myocardial displacement of the basal septal and lateral walls (PMDbase), and the temporal coefficient of variation of the PMD in six LV regions (CV-PMDLV) were measured. The patients were divided into responders (whose LV end-systolic volume decreased by ≥15% during a 27 ± 9 months follow-up) and nonresponders.
Results: Before CRT, IVCDbase was similar in both groups, and remained unchanged within the 1st month of CRT in both groups. However, before CRT, IVCDmax was greater in responders than in nonresponders (P < 0.05), and decreased only in the responders during CRT (P < 0.05). No significant difference was observed in PMDbase or CV-PMDLV between the two groups, before or during CRT.
Conclusions: TSI was useful to measure IVCDmax. A greater IVCDmax before CRT that decreased shortly after onset of CRT may predict long-term clinical improvement in CRT recipients.