Characteristics of a fast transient outward current in guinea pig trigeminal motoneurons

A fast transient voltage dependent outward current (TOC) in trigeminal motoneurons (TMNs) was studied in guinea pig brainstem slices by use of sharp electrodes in combination with single electrode voltage clamp techniques. In solutions containing TTX, low Ca2+/Mn2+ and 20 mM TEA this current activated around -55 to -60 mV from holding potentials negative to resting potential, obtained its peak amplitude within 5 ms and decayed as a single exponential with a time constant of 6-8 ms. Half maximal values for inactivation and activation were -72 and -37 mV, respectively. Bath application of 5 mM 4-AP suppressed this current by approximately 90% and eliminated the early depolarizing transient membrane rectification observed in response to a constant depolarizing current pulse, prolonged the action potential duration, and reduced the threshold voltage and delay to onset of the action potential. It is suggested that this current resembles the typical A-current observed in many CNS neurons and, as a result of its voltage and time dependent properties, could contribute to control of motoneuronal discharge and timing of burst onset during rhythmical jaw movements. Therefore, any cellular models of masticatory activity should include the properties of this current.     

Optokinetic nystagmus in progressive retinal degeneration.

Studied optokinetic nystagmus (OKN) in normally pigmented and delayed amelanotic (DAM) strains of domestic chickens (N?=?18). The DAM line is characterized by postnatal feather and ocular depigmentation accompanied by progressive retinal degeneration that occurs, initially and most severely, in the central retina. Results indicate a close association between the extent of ocular pigment loss and relative reduction in OKN responsiveness in DAMs. The directional asymmetry of OKN responses, which normally occurs with monocular temporal-to-nasal (T–N) but not with N–T stimulation, was altered in relation to the extent of ocular amelanosis among DAMs. In particular, T–N OKN responses were progressively reduced as amelanosis of the central retina increased in severity. In DAMs with moderate to severe reductions in T–N responsiveness, relatively little reduction occurred in N–T responsiveness. The central retina, therefore, appears to play a major role in mediating responses to T–N stimulation, whereas the peripheral retina mediates both directions of response. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Manifest and latent functions in psychotherapy.

Replies to W. G. Herron's (see PA, Vol 52:Issue 4) criticism of the author's original article. Additional evidence is offered that traditional psychodynamic psychotherapy does not fulfill its manifest function to help individuals achieve "mental health"; its persistence as an ideology and in clinical practice can be explained only on the basis of its latent function as a means of social control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Congenital periodic alternating nystagmus. Diagnosis and Management

PURPOSE: The purpose of the study is to investigate diagnostic criteria and treatment methods for patients with congenital periodic alternating nystagmus (PAN). METHODS: A retrospective analysis was performed of clinical findings and serial eye movement recordings of patients with congenital PAN. Eighteen patients observed from 1983 through 1996 and diagnosed with congenital PAN are included. Five of these have ocular or oculocutaneous albinism. Nine of the 18 patients were treated. Three had Kestenbaum operations before referral to the authors, one was treated with baclofen, and five had large recessions of the four horizontal recti. The studied parameters included visual acuity (VA) and abnormal head posture (AHP); temporal aspects of PAN cycle, nystagmus waveforms, frequency, amplitude, and velocity; as well as mean foveation fraction, a mean percentage of the nystagmus cycle spent at retinal slip velocities less than 10 degrees per second. RESULTS: The authors diagnosed PAN in 9% of patients with congenital nystagmus, although most had not been diagnosed with PAN before referral, despite changing nystagmus. Sixteen patients had AHP, typically shifting. The PAN cycle was of variable duration, often with asymmetric right- and left-beating components. Although horizontal jerk nystagmus with accelerating slow phase was predominant, other waveforms were encountered in the active phase of PAN. In the quiet phase (close to null zone), similar, but less intense, oscillations than those in the active phase were characteristic. Half of the patients showed a combination of waveforms in both phases. Baclofen treatment was unsuccessful. Patients who had Kestenbaum procedures remained with AHP in the original or opposite direction, without change in nystagmus or VA. Large recessions of four horizontal recti proved uncomplicated. This treatment improved, at least for several years, AHP and VA and caused favorable changes in nystagmus parameters in all patients. Mean foveation fractions increased significantly after surgery. CONCLUSIONS: Congenital PAN often is underdiagnosed. Differing waveforms may indicate PAN. Evaluation of nystagmus, especially before surgery, for at least 3 minutes, preferably with eye movement recordings, is necessary to diagnose PAN and perhaps prevent Kestenbaum procedures, which seem inappropriate. Large horizontal recti recessions seem to provide safe and promising treatment.     

Characteristics of virus-specific CD8(+) T cells in the liver during the control and resolution phases of influenza pneumonia

Dissection of the primary and secondary response to an influenza A virus established that the liver contains a substantial population of CD8(+) T cells specific for the immunodominant epitope formed by H-2Db and the influenza virus nucleoprotein peptide fragment NP366-374 (DbNP366). The numbers of CD8(+) DbNP366(+) cells in the liver reflected the magnitude of the inflammatory process in the pneumonic lung, though replication of this influenza virus is limited to the respiratory tract. Analysis of surface phenotypes indicated that the liver CD8(+) DbNP366(+) cells tended to be more "activated" than the set recovered from lymphoid tissue but generally less so than those from the lung. The distinguishing characteristic of the lymphocytes from the liver was that the prevalence of the CD8(+) DbNP366(+) set was always much higher than the percentage of CD8(+) T cells that could be induced to synthesize interferon gamma after short-term, in vitro stimulation with the NP366-374 peptide, whereas these values were generally comparable for virus-specific CD8(+) T cells recovered from other tissue sites. Also, the numbers of apoptotic CD8(+) T cells were higher in the liver. The results overall are consistent with the idea that antigen-specific CD8(+) T cells are destroyed in the liver during the control and resolution phases of this viral infection, though this destruction is not necessarily an immediate process.     

Information-theoretic latent distribution modeling: Distinguishing discrete and continuous latent variable models.

Distinguishing between discrete and continuous latent variable distributions has become increasingly important in numerous domains of behavioral science. Here, the authors explore an information-theoretic approach to latent distribution modeling, in which the ability of latent distribution models to represent statistical information in observed data is emphasized. The authors conclude that loss of statistical information with a decrease in the number of latent values provides an attractive basis for comparing discrete and continuous latent variable models. Theoretical considerations as well as the results of 2 Monte Carlo simulations indicate that information theory provides a sound basis for modeling latent distributions and distinguishing between discrete and continuous latent variable models in particular. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Diagnostic evaluation of the cervical nystagmus in cervical torsion test

The long-term effects of streptozotocin (30-70 mg/kg) were studied on plasma glucose and insulin levels, islet morphology, and glucose-stimulated insulin secretion in rats. In addition, the protective effect of short-term (7 days) insulin treatment on streptozotocin-induced diabetes was examined. Streptozotocin administration at dose levels exceeding 40 mg/kg resulted in a long-term, stable hyperglycemia with no insulin response to glucose at 3 months and with a marked derangement of islet morphology (few insulin cells, accumulation of glucagon cells). In contrast, at 30 and 40 mg/kg, streptozotocin induced a transient diabetes. Thus, the blood glucose levels, being elevated at days 1-7, returned to normal levels within 10 days after streptozotocin administration and the glucose-induced insulin secretion, being absent at day 1, was normal at 3 months. Furthermore, the islet morphology was also normal in these groups at 3 months. Short-term (7 days) insulin treatment normalized the long-term diabetes in rats given 50 mg/kg streptozotocin, but not in rats given 60 or 70 mg/kg streptozotocin. Thus, after insulin treatment, all rats receiving 50 mg/kg streptozotocin returned to normoglycemia within the following 2 weeks, and the glucose-induced insulin secretion was normal after 3 months, as was islet morphology.(ABSTRACT TRUNCATED AT 250 WORDS)     

Benign postural vertigo and nystagmus of the horizontal semicircular canal

Benign paroxysmal vertigo and nystagmus are induced not only by the posterior but also by the horizontal semicircular canal. Benign positional nystagmus of the horizontal canal is more often observed than was previously thought. In 10 patients we analyzed the characteristics and the variability of nystagmus which accompanies positional vertigo of the horizontal canal. There are two forms of nystagmus: primary-geotropic, most often paroxysmal nystagmus (7 patients), and primary-apogeotropic, non-paroxysmal nystagmus (3 patients). Interestingly, in 2 patients with the primary-apogeotropic form the nystagmus converted during the examination into the primary-geotropic form. The reverse was not observed. We discuss the possible pathophysiological mechanisms which could be relevant for provoking manoeuvres.     

MAX phases in titanium and aluminum alloys

The crystalline structures in the Ti-Al-C and Ti-Si-C systems are analyzed, and experiments are conducted with VT6 titanium alloy and eutectoidal Silumin (Al-12% Si) subjected to electroexplosive alloying and electron-beam treatment. Diffraction analysis reveals the formation of MAX phases (Ti₃SiC₂ and Ti₃AlC) in the modified layer of these alloys.     

Effect of tensilon on the behavior of optokinetic nystagmus in myasthenia

In 14 myasthenics tensilon test was performed together with electronystagmographic recording of optokinetic nystagmus. The mean amplitude of deflections and the mean frequency of nystagmus were calculated before and after intravenous administration of tensilon 10 mg. The results were compared with those obtained in a control group. The test was positive in 11 myasthenics: the amplitude and frequency of nystagmus beats increased and extinction at the end of the test was absent or diminished. In the control group the test was negative, with the exception of 3 cases in which a slight increase in amplitude and frequency was observed. The authors stress the advantages and disadvantages of tensilon test and state that it is diagnostically valuable in myasthenia and myasthenic syndromes in subjects sensitive to the drug.     

The influence of linear acceleration on optokinetic nystagmus in human subjects

The influence of linear acceleration on optokinetic nystagmus (OKN) was studied in human subjects. Linear acceleration was applied to the subjects by means of the parallel swing and also by the transfer of the subjects in one direction, either right or left. The cortical form of OKN increased the frequency, amplitude, and eye speed of the slow phase. Of the three, the increase in eye speed was the most pronounced. The subcortical form of OKN was not only increased but was also disturbed by the linear acceleration. When the compensatory eye movement with linear acceleration and the slow phase of OKN were in the same direction, the nystagmus increased remarkably. Contrarily, when the two directions were opposed to each other, nystagmus was inhibited. These results proved that the otolithic organs are not only able to promote but also to inhibit visual function.