Electrode Positioning for Reliable Telemetry ECG Recordings During Social Stress in Unrestrained Rats

We describe a surgical procedure for optimizing the location of telemetry ECG leads in rats. The new location was aimed at obtaining an accurate representation of ECG features throughout the cardiac cycle by limiting the voltage instability usually observed during intense somatomotor activity and improving the signal-to-noise ratio. The two electrodes (wire loops) were fixed on the dorsal surface of the xiphoid process and in the anterior mediastinum close to the right atrium. The implantation procedure was fast, little invasive, and allowed animals to completely recover from intervention. The performance of the “improved” location (IL, n = 10) with respect to two subcutaneous (SC) positionings (“conventional positioning,” CSP, n = 5; “updated location,” USL, n = 5) was evaluated by comparing ECGs obtained in baseline, stress and recovery conditions and during different behavioral activities (immobility and grooming). The resident-intruder test (emotional/physical challenge) was chosen as experimental stress paradigm. The noise level of ECGs obtained from IL rats was lower than in CSP and USL animals, in all recording conditions. Percentages of correctly recognized beats (CRBs) over the total number of beats (TBs) were significantly higher in IL rats than in CSP and USL animals, both in baseline conditions (99% vs. 11% and 40%) and situations involving high somatomotor activity (stress: 97%, 5% and 16%; recovery: 97%, 7%, and 15%) (p < 0.01). The performance of IL as compared to CSP and USL was also better when percentages during grooming and immobility were considered (grooming: 93% vs. 4% and 23%; immobility: 97%, 6%, and 33%; p < 0.01).     

DIFFERENTIATION PATHWAYS IN PRIMARY INVASIVE BREAST CARCINOMA AS SUGGESTED BY INTERMEDIATE FILAMENT AND BIOPATHOLOGICAL MARKER EXPRESSION

The expression of intermediate filament proteins (IFPs) in 65 primary breast carcinomas was analysed by a panel of specific antibodies. Results were integrated with the oestrogen and progesterone receptor (ER and PGR) status, Ki-67 marking, and epidermal growth factor receptor (EGFr) expression. Invasive breast carcinomas could be divided into three main groups: group 1 revealed positivity only for ‘simple epithelial’ cytokeratins (CKs 7, 8, 18, and 19); group 2 also stained with the antibodies K8.12 and 34βE12; while group 3 showed co-expression of CKs 14 and 17, vimentin, and α-smooth muscle actin. Group 3 consistently comprised tumours with the highest Ki-67 levels, EGFr positivity, and ER-PGR negative status. On the other hand, groups 1 and 2 usually exhibited a positive hormonal status, lower proliferative activity, and EGFr negativity. The results of this study indicate that the determination of IFPs can significantly contribute to the identification of groups of patients with different biopathological settings and possibly different clinical behaviour.     

DIFFERENTIAL GROWTH OF N- AND S-TYPE HUMAN NEUROBLASTOMA CELLS XENOGRAFTED INTO SCID MICE. CORRELATION WITH APOPTOSIS

This study concerns the role of apoptosis in the growth of human neuroblastomas transplanted into immunodeficient SCID mice. Human neuroblastoma cell lines may consist of one or more distinct phenotypes including the neural ‘N-type’ and flat substrate-adherent ‘S-type’. A differential phenotype-specific proliferation was apparent among S- and N-type cell clones transplanted into SCID mice when compared with the wild-type SK-N-BE(2) cell line. This differential growth capacity of the tumours was correlated with spontaneous apoptosis. Another SK-N-BE(2)-derived cell line (TGA), displaying high levels of apoptosis upon stable transfection with the full length ‘tissue’ transglutaminase (tTG) cDNA, was unable to induce tumour development when xenografted into SCID mice. To support these observations, the expression of apoptosis-related genes (i.e., bcl-2, p53, and tTG) in the various neuroblastomas was also investigated.     

Noninvasive Classification of Ventricular Preexcitation with Unshielded Magnetocardiography and Transesophageal Atrial Pacing and Follow-Up

Background: Ventricular preexcitation (VPx) is usually localized noninvasively by means of electrocardiogram (ECG) algorithms, which vary in their concordance levels. Contactless magnetocardiography (MCG) has been used as an alternate 3-dimensional (3D) method of accessory pathways (AP) localization. The sensitivity of MCG can be increased for preoperative evaluations and planning of ablation procedures by combining it with transesophageal pacing (TEP) and electrophysiological (EP) studies. This study compared the accuracy of VPx localization with MCG with ECG algorithms, and examined the increment in diagnostic accuracy achievable with TEP.
Methods: Multisite mapping from the anterior chest wall was performed with a 36-channel MCG system. TEP allowed the evaluation of anterograde conduction properties and inducibility of arrhythmias. The reproducibility of the test and follow-up was examined in 88 patients with Wolff–Parkinson–White (WPW) syndrome. The accuracy of MCG localization was reevaluated during pacing-induced maximal VPx in 36 patients in whom, during MCG, the degree of VPx was highest during TEP. The gold standard for validation was effective ablation of the AP.
Results: The MCG classification of VPx was accurate in 94% of AP, versus 64% and 67% with ECG, during sinus rhythm and during pacing-induced maximal VPx, respectively. In 4.5% of cases with unclear ECG localization, MCG suggested a complex septal VPx. In all patients with successful ablations, the 3D MCG localization of the AP corresponded to the ablation site.
Conclusions: MCG was more accurate than ECG for the classification of VPx and provided additional information in the non-invasive EP assessment of patients with WPW syndrome.     

Effect of lamotrigine on EEG paroxysmal abnormalities and background activity: a computerized analysis

1 Little information is available about the action of lamotrigine (LTG) on EEG paroxysmal abnormalities and background activity. On the contrary, several clinical trials have shown the therapeutic efficacy of the drug in preventing partial and generalized seizures.
2 We performed computerized EEG monitoring in 21 patients suffering from focal and generalized epilepsy before and 4 months after addition of LTG. The anticonvulsant modified the EEG ictal events by reducing their frequency and duration. A statistically significant decrease of the interictal spikes was observed. The decrease involved mainly the spreading component of the interictal events leading to a better spatial definition of the epileptic focus.
3 In the presence of LTG, generalized tonic-clonic attacks were completely controlled, whereas partial seizures were decreased.
4 The EEG background activity was not modified by the addition of the drug.
5 Our findings suggest a specific role for LTG in the generation and propagation processes of epileptiform activity without interfering with the EEG background activity.     

IMMUNE ACTIVATION AS EFFECT MODIFIER OF ATHEROGENESIS IN CHRONIC INFECTION

Although no study has proven that infections cause atherosclerotic disease, findings suggest that exposure to infections such as Chlamydia pneumoniae, Helicobacter pylori, and bacterial infections related to periodontal disease or smoking might influence the development of heart, carotid, and peripheral vascular disease. Epidemiological data convincingly demonstrate risk for atherosclerotic disease associated with bacterial infection and endotoxemia; however, the independent contributions to disease and pathogenic mechanisms of endotoxin remained elusive. Investigation into this relation tested the correlation between endotoxin and neopterin. Data indicated that neopterin, which reflects immune activation of monocytes/macrophages, functions as atherogenic effect modifying factor on the effects of endotoxin. We hypothesize that immune activation via induction of endotoxin hyperresponsiveness determines the atherogenic potential of Gram-negative infections.     

CELLULAR KINETIC AND PHENOTYPIC HETEROGENEITY IN AND AMONG BURKITT'S AND BURKITT-LIKE LYMPHOMAS

This study asks whether the known genotypic heterogeneity within and between endemic or sporadic Burkitt's lymphomas (eBLs and sBLs, n=10 each), and Burkitt-like lymphomas (BLLs, n-12), is reflected in divergent cytokinetics and related immunophenotypes. There was strong evidence that eBL and BLL grow markedly faster than sBL, as shown by differences in mitotic and apoptotic indices. Furthermore, in BLL, the median percentage of neoplastic cells immunoreactive for the bcl-2 protein was much higher than that observed in eBL and sBL. The reverse was true for the median fraction of cells containing c-myc protein. In eBL and sBL, the median fraction of bcl-6 protein-positive cells reached values above 50 per cent, while cells of 8/12 BLLs did not contain detectable amounts of this protein. This observation indicates that in this respect, eBL and sBL resemble normal germinal centres of lymphatic tissue much more than do BLL. Evidence for infection of neoplastic cells by the Epstein-Barr virus (EBV) was observed in 9/10 cases of eBL and in 3/10 of sBL, but not in BLL. EBV-positive lymphomas were associated with distinctly lower apoptotic indices and smaller median percentages of bcl-6-positive cells than EBV-negative tumours. © 1997 John Wiley & Sons, Ltd.