Neural control of fast-regular saccades and antisaccades: an investigation using positron emission tomography

 Regional cerebral blood flow changes related to the performance of two oculomotor tasks and a central fixation task were compared in ten healthy human subjects. The tasks were: (a) performance of fast-regular saccades; (b) performance of voluntary antisaccades away from a peripheral cue; (c) passive maintenance of central visual fixation in the presence of irrelevant peripheral stimulation. The saccadic task was associated with a relative increase in activity in a number of occipitotemporal areas. Compared with both the fixation and the saccadic task, the performance of antisaccades activated a set of areas including: the superior and inferior parietal lobules, the precentral and prefrontal cortex, the cingulate cortex, and the supplementary motor area. The results of the present study suggest that: (a) compared with self-determined saccadic responses the performance of fast regular, reflexive saccades produces a limited activation of the frontal eye fields; (b) in the antisaccadic task the inferior parietal lobes subserve operations of sensory-motor integration dealing with attentional disengagement from the initial peripheral cue (appearing at an invalid spatial location) and with the recomputation of the antisaccadic vector on the basis of the wrong (e.g., spatially opposite) information provided by the same cue. Received: 20 May 1996 / Accepted: 28 January 1997     

Well-being therapy of generalized anxiety disorder

BACKGROUND: There is increasing awareness that the goal of treatment in generalized anxiety disorder (GAD) should not simply be a response, but restoration of normal function. The aim of this study was to apply a novel psychotherapeutic approach for increasing the level of remission in GAD. METHODS: Twenty patients with DSM-IV GAD devoid of comorbid conditions were randomly assigned to 8 sessions of cognitive behavioral therapy (CBT) or the sequential administration of 4 sessions of CBT followed by other 4 sessions of well-being therapy (WBT). Assessment methods included the Anxiety and Depression Scales of Paykel's Clinical Interview for Depression, Ryff's Psychological Well-being Scales and Kellner's Symptom Questionnaire. A one-year follow-up was undertaken. RESULTS: Significant advantages of the CBT-WBT sequential combination over CBT only were observed with both observer and self-rated methods after treatment. Such gains were maintained at follow-up. CONCLUSIONS: These preliminary results suggest the feasibility and clinical advantages of adding WBT to the treatment of GAD. They lend support to a sequential use of treatment components for achieving a more sustained recovery.     

Characterization of the large-conductance Ca-activated K channel in myocytes of rat saphenous artery

We used the patch-clamp method to characterize the BK channel in freshly isolated myocytes from the saphenous branch of the rat femoral artery. Single-channel recordings revealed that the BK channel had a conductance of 187 pS in symmetrical 150 mM KCl, was blocked by external tetraethylammonium (TEA) with a KD(TEA) of approx. 300 microM at +40 mV, and by submicromolar charybdotoxin (CTX). The sensitivity of the BK channel to Ca was especially high (KD(ca) approx. 0.1 microM at +60 mV) compared to skeletal muscle and neuronal tissues. We also investigated the macroscopic K current, which under certain conditions is essentially sustained by BK channels. This conclusion is based on the findings that the macroscopic current activated upon depolarization follows a single exponential time course and is virtually fully blocked by 100 nM CTX and 5 mM external TEA. We made use of this occurrence to assess the voltage and Ca dependence of the macroscopic BK current. In intact myocytes, the BK channel showed a strong and voltage-dependent reduction of the outward current (62% at +40 mV), most likely due to block by intracellular Ba and polyamines. The results obtained from macroscopic and unitary current indicate that approx. 2.5% of the BK channels are active under physiological conditions, sustaining approx. 20 pA of outward current. Given the high input resistance of these cells, few BK channels are required to open in order to cause a significant membrane hyperpolarization, and thus function to limit the contraction resulting from acute increases in intravascular pressure, or in response to hypertensive pathologies.     

Changes in EEG activity and hypothalamic temperature as indices for non-REM sleep to REM sleep transitions

A shift of physiological regulations from a homeostatic to a non-homeostatic modality characterizes the passage from non-NREM sleep (NREMS) to REM sleep (REMS). In the rat, an EEG index which allows the automatic scoring of transitions from NREMS to REMS has been proposed: the NREMS to REMS transition indicator value, NIV [J.H. Benington et al., Sleep 17 (1994) 28-36]. However, such transitions are not always followed by a REMS episode, but are often followed by an awakening. In the present study, the relationship between changes in EEG activity and hypothalamic temperature (Thy), taken as an index of autonomic activity, was studied within a window consisting of the 60s which precedes a state change from a consolidated NREMS episode. Furthermore, the probability that a transition would lead to REMS or wake was analysed. The results showed that, within this time window, both a modified NIV (NIV(60)) and the difference between Thy at the limits of the window (Thy(D)) were related to the probability of REMS onset. Both the relationship between the indices and the probability of REMS onset was sigmoid, the latter of which saturated at a probability level around 50-60%. The efficacy for the prediction of successful transitions from NREMS to REMS found using Thy(D) as an index supports the view that such a transition is a dynamic process where the physiological risk to enter REMS is weighted at a central level.     

Auditory brainstem response in premenopausal women taking oral contraceptives

BACKGROUND: The aim of this prospective study was to evaluate the effects of the new monophasic oral contraceptives on the audiological system in premenopausal women. METHODS: The auditory brainstem response (ABR) was measured in 94 women during the follicular, periovular and luteal phases of one menstrual cycle in which ovulation was confirmed using sonography and serum progesterone concentration. The latencies for waves I, III and V were determined, and the inter-peak intervals were calculated for waves I-III, I-V and III-V. All 94 women began taking oral contraceptives: 23 women used 20 microg ethinyl estradiol (EE) plus 150 microg desogestrel, 24 women used 30 microg EE plus 75 microg gestodene, and 47 women used 15 microg EE plus 60 microg gestodene. During the third month of contraceptive intake, each subject was again tested for ABR, as above. RESULTS: The wave latencies and inter-peak intervals showed shorter values during the periovular phase with respect to the luteal phase (P < 0.05), the follicular phase for wave I and for inter-peak interval I-V (P < 0.05) of the menstrual cycle. All of the ABR results in pill users were statistically different from those of the periovular phase (P < 0.05), though similar to those of both the luteal and follicular phases (P = NS). CONCLUSIONS: ABR seems to depend on the variations of ovarian steroids during the menstrual cycle and during oral contraceptive intake.     

Good Safety Profile and Efficacy of Leucocyte Interferon-α in Combination with Oral Ribavirin in Treatment-Naive Patients with Chronic Hepatitis C

Background: The differential tolerability profile of various interferon (IFN)-α preparations used in combination with ribavirin for the treatment of chronic hepatitis C needs to be elucidated. Approximately 8% of patients receiving recombinant IFNα-2b plus ribavirin discontinue treatment because of adverse events. Human leucocyte IFNα is deemed to have a better safety profile than recombinant IFNα. We therefore compared the safety profile and efficacy of ribavirin combined with leucocyte IFNα or with recombinant IFNα-2b in treatment-naive patients with chronic hepatitis C. Study design: We randomised 423 patients to either leucocyte IFNα 3MU three times weekly plus ribavirin (210 patients) or the same dose of recombinant IFNα-2b plus ribavirin (213 patients). Patients were treated for 24 weeks and followed-up for a further 48 weeks. The primary endpoint was the safety profile of the two therapies; the secondary endpoint was the rate of sustained response. Results: In patients receiving leucocyte IFNα, the total number of adverse events was lower than in the group receiving recombinant IFNα (259 vs 441 patients), and the percentage of patients discontinuing treatment because of adverse events or laboratory abnormalities was significantly reduced (4% vs 11%; p = 0.013). Sustained response was observed in 47% of patients receiving leucocyte IFNα plus ribavirin and in 44% of patients receiving IFNα-2b plus ribavirin. Conclusions: Both therapeutic regimens were effective in inducing a sustained response in naive patients. However, the safety profile of leucocyte IFNα plus ribavirin was more favourable than that observed with the administration of recombinant IFNα-2b plus ribavirin, suggesting that leucocyte IFNα may be an alternative option in patients with reduced tolerability to other IFNs.     

Comparative genomic hybridization analysis of hepatoblastoma reveals high frequency of X-chromosome gains and similarities between epithelial and stromal components

Hepatoblastoma (HB) is the most common liver tumor in childhood and differs in its environmental risk factors and genetic background from hepatocellular carcinoma. HB is associated with inherited conditions such as familial adenomatous polyposis and Beckwith-Wiedemann syndrome, suggesting the importance of genetic abnormalities in the pathogenesis and progression of this disease. It has a very polymorphous morphology. A diverse range of cytogenetic alterations has been reported to date, the most frequent being trisomy 2 and trisomy 20. Thirty-five HB specimens from 31 patients (22 purely epithelial, 4 purely mesenchymal, 9 mixed) were examined by comparative genomic hybridization (CGH), a technique that enables us to screen the entire tumor genome for genetic losses and gains. Our aims were as follows: (1) to characterize chromosome abnormalities that appear in this tumor and (2) to identify possible differences between different histologic subtypes of HB. We found significant gains of genetic material, with very little difference in the number and type of alterations between the different histologic components of HB. The most frequent alterations were gains of Xp (15 cases, 43%) and Xq (21 cases, 60%). This finding was also confirmed by fluorescent in situ hybridization performed on nuclei extracted from 6 specimens. Other common alterations were 1p-, 2q+, 2q-, 4q-, and 4q+. We found no difference between different histologic subtypes, a finding that may be in agreement with the hypothesis of a common clonal origin for the different components. An hitherto-unreported high frequency of X chromosome gains may support the assumption that X-linked genes are involved in the development of this neoplasm.     

Quantitative Correlation between Steric Defects and Thermal Behavior in Highly Syndiotactic Polystyrene: A Study Based on DSC and 13C NMR Spectroscopy

Several syndiotactic polystyrene (sPS) samples have been synthesized by using different catalytic systems. Their stereochemistry has been determined by ¹³C NMR spectra in both the aliphatic CH₂ and aromatic C₁ resonance regions. The observed peaks have been unambiguously assigned to specific hexads and heptads, respectively, and their intensities have been used to draw the percent of defects (meso dyads) in the polymer chains. On the hypothesis that chain defects are at the origin of chain folding and thus determine the thickness of crystalline lamellae, we performed differential scanning calorimetry (DSC) analysis on the same samples, and their thermal parameters were measured. A model was developed to determine the amount of steric defects from the DSC melting‐peak profiles, and the results obtained were compared with the NMR results. A satisfactory agreement was found (correlation factor 0.96) in the explored range of defect concentrations (up to 2.5% of meso dyads). The possible influence of the extraction procedure of the amorphous fraction was found to be negligible. Thus, information on stereochemistry can be obtained from DSC experiments starting from as‐prepared (not extracted) samples.