Ultrathin Monolithic Zirconia Veneers: Reality or Future? Report of a Clinical Case and One-year Follow-up.

Yttria-stabilized polycrystalline zirconia ceramics have greatly advanced over the past few years. High-translucent zirconia is a newly introduced ceramic that affords high strength and esthetics and that has significantly increased the clinical indications of monolithic zirconia restorations. Thus, the purpose of this case report was to evaluate the performance of ultrathin monolithic zirconia veneers adhesively luted to enamel surfaces after minimally invasive preparations; in addition, we aimed at presenting a clinical protocol for zirconia surface treatment in order to promote bonding effectiveness to resin cement. This type of restoration presented very acceptable esthetic results and decreased the risk of fracturing the veneer during try-in and clinical use. The results were still satisfactory after one-year follow-up. However, randomized, prospective, controlled clinical trials are required to determine the long-term clinical durability of this treatment.

Gamma-band oscillations in the "barrel cortex" precede rat's exploratory whisking.

Cortical oscillations have been reported in relation to animal behavior and may have important roles in neuronal information processing such as "binding". We considered oscillatory activities in the primary somatosensory cortex of rats as a preparatory state for sensory processing and investigated the temporal relationship between gamma oscillation (25-45 Hz) onset in the somatosensory cortex (the barrel cortex) and rat's whisking as tactile exploratory behavior. The gamma oscillations of local field potentials preceded the whisking in 52/83 cases (63%). The mean lead time of the oscillations, defined as time from the oscillation onset to the whisking, was 268 ms (+/- 123, S.D.). These preceding gamma oscillations lasted to the onset of whisking. Furthermore, we investigated the temporal relationship during the other two behavioral states: a still but alert state and a state with tactile stimulation of the whiskers. In the state with tactile stimulation, gamma oscillations followed the stimulation, and in the still but alert state, significant gamma oscillation was not observed. The gamma oscillations that precede the whisking are thought to reflect anticipatory activities in the barrel cortex for the subsequent somatosensory input from the whiskers, which could represent a mechanism for rapid processing of expected sensory information.

Identification of the site of Epstein-Barr virus persistence in vivo as a resting B cell.

Epstein-Barr (EBV) is a powerful immortalizing virus for human B lymphocytes in vitro and is associated with several human neoplasias in vivo. Previously, we have shown that the majority of EBV-infected cells in the peripheral blood of healthy, persistently infected individuals do not express the activated phenotype, e.g., high levels of cell surface CD23 and CD80 (B7), characteristically expressed on in vitro-immortalized cells. Here, we show that > or = 90% of the CD23-, virus-infected cells in the peripheral blood are in G0 and therefore resting. The remaining cells may be G1 arrested, but we were unable to detect a significant number of cells traversing the S-G2-M stages of the cell cycle. The mRNA for LMP2A, but not EBNA1 originating from Qp, was readily detected in this population, and these cells appear competent in the processing and presentation of antigen by class I major histocompatibility complex. We propose that these resting B cells are the site of long-term latent persistence for EBV. We further propose that the persistence of the virus in a resting B7- B cell provides an important mechanism to escape immunosurveillance. The demonstration that EBV can persist latently in a resting B cell means that the immortalizing functions of EBV can be down regulated in a normal B cell. This conclusion has important implications for understanding and controlling EBV-associated neoplasia.

The demonstration of serum interleukin-8 and superoxide dismutase in Adamantiades-Behçet's disease.

Serum interleukin-8 (IL-8) production was measured in 43 Adamantiades-Behçet's disease (A-BD) patients and in 46 healthy volunteers using a sandwich enzyme-linked immunosorbent assay (ELISA). The mean serum IL-8 level of the patients (14.6 +/- 3 pg/ml) was significantly higher than that of controls (10.8 +/- 3 pg/ml, P < 0.05). Since IL-8 is known to have proinflammatory properties, it may play some role in the pathogenesis of A-BD. We also investigated the activity of serum superoxide dismutase (SOD) in the 43 patients with A-BD and in the 46 healthy volunteers. Serum SOD activity was markedly increased in the patients with A-BD (13.1 +/- 3%), especially in active A-BD, compared with that in the healthy volunteers (6.7 +/- 3%, P < 0.01). Our results suggest the involvement of IL-8 and SOD in the pathogenesis of A-BD as seen in other inflammatory diseases.

Quadrupedal locomotor movements in monkeys (M. Fuscata) on a treadmill: kinematic analyses.

Three adult Japanese monkeys (M. fuscata: body weights 4.5-8.5 kg) were trained to walk quadrupedally on a surface of a moving treadmill (walking length and width: 150 cm and 60 cm, treadmill speed: 0.4-1.7 m s-1. At any different constant treadmill velocity, the monkeys exhibited a diagonal pattern of locomotor movements. Side views of locomotor patterns were photographed (10 frames s-1 and videotaped (250 frames s-1. Depictions of representative locomotor patterns and stick figures of forelimb, hindlimb and trunk movements were made from the serial photographs and videotapes, respectively. Similarities and differences in the kinematics of non-human primate locomotor movements are discussed in relation to those of subprimate terrestrial animals.

Tactile experience determines the organization of movement representations in rat motor cortex.

We mapped movement representations in motor cortex of rats that had their mystacial vibrissae (whiskers) clipped continually for various periods during their development. In animals clipped since birth, and in adult animals clipped for 5 days, there was a significant reduction in the ratio of whisker to forelimb representation areas. Allowing the whiskers to regrow for at least 72 h resulted in normal-appearing representation patterns. The plasticity of motor representations induced by whisker clipping, and that following whisker regrowth, were not age dependent. These findings indicate that a relatively innocuous procedure that restricts sensory and motor functions results in pronounced, and reversible, changes in the functional organization of the motor cortex.

The 'functional connection' of neurones in relation to behavioural states in rats.

In order to investigate whether dynamics of neuronal networks change during differing behavioural states, the 'functional connection' between neurones in the rat vibrissal sensorimotor system during two different behavioural states (active vs passive whiskering) were revealed using time-dependent scatter diagrams. The functional connection between neurones in the vibrissal motor (MCx) and sensory (SCx) cortices and the superior colliculus (SC) changed depending on the behavioural state. In the rat vibrissal system, the pattern of correlated activities among neurones in the MCx, SCx and SC may play an important role in determining behaviour.

Is EBV persistence in vivo a model for B cell homeostasis?

We have measured the absolute numbers of EBV-infected B cells in the peripheral blood of healthy persistently infected individuals. Single measurements on a panel of 15 healthy individuals demonstrate that the frequency varies over a wide range from 1-50 per 10(6) B cells. Repeat measurements over 1-3.5 years on several individuals whose frequencies varied over a 10-fold range showed that the variation does not represent the fluctuation in the frequency that can occur within an individual; rather, the frequencies are specific to the individual. The frequency within an individual measured over time is stable and contributes less than 10% to the variance seen in the whole population. These measurements suggest that the level of EBV-infected B cells is tightly regulated and we propose that the same homeostatic mechanisms that regulate the levels of normal B cells also regulate B cells latently infected with EBV.

Epstein-Barr virus and the B cell: that's all it takes.

Recent experiments demonstrate that a much broader range of B cells harbor Epstein-Barr virus (EBV) in vivo than was previously expected from in vitro studies. In this review it is argued that EBV persists in vivo by integrating its biology with that of the normal B cells within which it resides, and that the B cell provides all the environments necessary for EBV to maintain its life cycle.

Basic neurophysiology of primate locomotion.

To initiate and terminate bipedal and quadrupedal locomotor movements, a smooth transition to and from standing is necessary. For this, integration of postural and locomotor control systems is required. Recent studies in nonhuman primates and other quadrupedal animals such as cats have clearly shown that there exist significant analogies between the primate species investigated (Macaca mulatta, Macaca fascicularis, and marmosets) and the cats regarding the spinal stepping generator or central pattern generator (CPG), supraspinal descending pathways which activate CPG, and the midbrain and brain stem postural and locomotor control structures. Further studies aimed at elucidating the differences and similarities in the manner of locomotor control among different animal species will help us in understanding the control mechanisms involved in both bipedal and quadrupedal locomotor movements in nonhuman primates.

Usefulness of the endotoxin test for assessing CAPD peritonitis by gram-negative organisms.

The endotoxin (ET) in cloudy peritoneal fluid was measured, and the usefulness of the method was examined. Thirteen continuous ambulatory peritoneal dialysis (CAPD) patients with an episode of peritonitis from December, 1993 to December, 1995 were studied. The peritoneal fluid was collected without contamination from the bags and divided into two batches. The ET was measured in one of them with the limulus amebocyte lysate (LAL) assay, and the other was cultured for bacteria. Among the 13 patients ET was positive in 7 Gram-negative bacteria were identified in all 7 cases. Two of these patients were transferred to hemodialysis. On the other hand, gram-positive bacteria were cultured in only four episodes of the 6 ET-negative patients, all of which were treated successfully with vancomycin. Microbiological culture of the dialysate is still necessary for the treatment of peritonitis. But it takes 24-48 hours to obtain microbiological results. The result of the ET test can be given within one and one half hours (and it has 100% sensitivity and specificity for gram-negative peritonitis) at presentation in the episodes. Therefore, the ET test of the dialysate is very effective for the therapy of peritonitis in CAPD.

The superior colliculus relays signals descending from the vibrissal motor cortex to the facial nerve nucleus in the rat.

Electrical stimulation of the vibrissal motor cortex (VMCx), the superior colliculus and the facial nerve nucleus elicits vibrissal movements. A possibility of the superior colliculus as one of the relay nuclei between the VMCx and the facial nerve nucleus was investigated by injecting an anterograde neural tracer, Phaseolus vulgaris leucoagglutinin (PHA-L), into the physiologically identified VMCx and a retrograde tracer, cholera toxin B subunit (CTb), into the facial nerve nucleus in Wistar rats. In the lateral half of the superior colliculus, the termination field of axons from the VMCx overlapped with the distribution field of projection neurons to the facial nerve nucleus. In some cases, PHA-L-labeled terminal swellings were closely apposed to the somas of CTb-labeled neurons. We conclude that signals descending from the VMCx are relayed through the lateral half of the superior colliculus to the facial nerve nucleus.

A novel form of Epstein-Barr virus latency in normal B cells in vivo.

We have developed a PCR assay that can detect a single Epstein-Barr virus (EBV) genome in the presence of 10(6) uninfected cells. Using this assay, we demonstrate that EBV persists, in the peripheral blood of all seropositive individuals tested, in CD19+, CD23-, and CD80 (B7)- B cells. We further show that the virus in these cells is latent, but readily reactivated to produce infectious immortalizing virus; therefore, these cells represent a true site of latent persistence. EBV was not significantly detected in monocytes or T cells. The frequency of infected cells in nine healthy donors varied from 23 to 625 per 10(7) B cells, but was relatively stable for each individual over the course of 2 years. We conclude that the EBV-infected cells in vivo are B cells with a nonactivated phenotype. This represents a novel form of latency in normal B cells.

Evaluation of the functional connectivity in the nervous system using time dependent scatter diagrams.

We investigated spike trains of the feline nervous system, which are considered to be non-stationary point processes characterized by changes of the functional interneuronal connectivities. Ordinary long-term averaged correlation methods are useful as processing time series data as a quasi-stationary point process, but not as a non-stationary point process. We depicted the joint impulse configuration scatter diagram proposed by D. H. Perkel et al. for subsets of the neural spike-train to find changes of functional connectivities. The time-dependent scatter diagram was generated by arranging these scatter diagrams in chronological order. Time-dependent scatter diagrams were generated for spike trains derived from the anterior ectosylvius sulcus, the coronal sulcus, the lateral bank of the presylvius sulcus, the medial wall of the presylvius sulcus, and the medial wall of the cruciate sulcus. The patterns of time-dependent scatter diagrams for these cortices are considered to change in relation to eye movement. Changes of these patterns correspond to those of the functional connectivities related to the dynamics of eye movement in the neural system.

Input-output organization of the rat vibrissal motor cortex.

The afferent and efferent connections of the vibrissal area of the rat motor cortex (VMCx) were investigated by injecting Phaseolus vulgaris leucoagglutinin (PHA-L) or wheat germ agglutinin-horseradish peroxidase into the physiologically defined VMCx. The VMCx formed reciprocal connections with the primary and secondary somatosensory cortex, lateral and ventrolateral orbital cortex, retrosplenial cortex, and perirhinal cortex. These corticocortical afferents originated from cell bodies in layers II-III and V, and some afferents originated from cell bodies in layer VI of the primary sensory cortex. All of the VMCs efferents terminated in layers I and V or layers I-III and V. The VMCx also formed reciprocal connections with the ventrolateral, ventromedial and centrolateral nucleus, the lateral portion of the mediodorsal nucleus and the posterior complex of the thalamus. It projected bilaterally to the caudate putamen, primarily ipsilaterally to the superior colliculus, anterior pretectal nucleus, and pontine nucleus, and mainly contralaterally to the oral part of the spinotrigeminal nucleus and the reticular formation around the facial nerve nucleus. Finally, injections of PHA-L into the superior colliculus demonstrated that this structure projected contralaterally to the lateral part of the facial nerve nucleus. These data suggest that the VMCx plays a key role in sensorimotor integration, through its extensive interconnectivity with numerous brain structures, and may modulate orientation behaviors by relaying processed information to the superior colliculus.

Projection from the sensory to the motor cortex is important in learning motor skills in the monkey.

1. The projection from the somatosensory cortex to the primary motor cortex has been proposed to play an important role in learning novel motor skills. This hypothesis was examined by studying the effects of lesions to the sensory cortex on learning of new motor skills. 2. We used two experimental paradigms to reveal the effects of lesions on learning of new motor skills. One task was to catch a food pellet falling at various velocities. The other task was to catch a food pellet from a rotating level. Both tasks required acquisition of novel motor skills. 3. The training was started after a lesion of the hand area in the somatosensory cortex of one hemisphere. In both tasks, monkeys had severe difficulty in learning the new skills with the hand contralateral to the ablated somatosensory cortex, compared with the hand contralateral to the intact hemisphere. 4. After acquisition of the motor skill in the hand contralateral to intact hemisphere, lesion of the somatosensory cortex hand area did not abolish the learned motor skill. 5. In control experiments, monkeys were trained to pick up a food pellet from a rotating board. This task did not necessitate acquisition of new motor skills, but could be performed by utilizing existing motor skills. Lesion in the somatosensory cortex before or after the training did not affect the execution of this task by either hand. 6. It is concluded that the corticocortical projection from the somatosensory to the motor cortex plays an important role in learning new motor skills, but not in the execution of existing motor skills.

Nucleus Z: a somatosensory relay to motor thalamus.

1. It was the aim of this study to show that nucleus Z of the cat medulla acts as a relay between the spinal cord and the ventral lateral (VL) nucleus of the motor thalamus. For this purpose, extracellular recordings were made from neurons that were antidromically identified by stimulation in the rostral thalamus, particularly VL, and orthodromically activated by electrical stimulation of the spinal cord and/or natural stimulation of the hindlimb. The electrophysiological work was complemented by anatomic work. Here, wheat germ agglutinin-horseradish peroxidase (WGA-HRP) was injected into nucleus Z and the termination sites of bulbothalamic projections were anterogradely labeled. 2. A total of 120 neurons were antidromically identified as projecting to thalamus: 101 to VL and 19 outside VL. The recording sites in nucleus Z were marked by dye injection or by electrolytic lesion. They were confined to a small region (roughly 1 mm in diameter), 2.8-3.7 mm rostral to obex, 2.9-3.8 mm lateral from the midline, and from the surface of the medulla to a depth of 1 mm. The antidromic latencies ranged between 0.8 and 3.2 ms, with no difference in latencies associated with location of neurons in nucleus Z or thalamic projection sites. 3. Injection of WGA-HRP labeled fibers and axon terminals in the contralateral thalamus. Terminal labeling was densest in the lateral parts of the mid- and caudal region of the VL nucleus and, to a lesser extent, in the adjacent rostrodorsal part of the ventro-posterior lateral (VPL) nucleus. The sites of terminal labeling in VL corresponded with location of antidromic stimulation sites. 4. Orthodromic activation of nucleus Z neurons was tested in response to electrical stimulation of the ipsilateral dorsolateral funiculus (which includes the dorsal spinocerebellar tract) and/or the dorsal columns. All neurons responded to stimulation of the dorsolateral funiculus (45/45). The responsiveness of 44 neurons was tested to stimulation of the dorsal columns. Only 8 of 44 tested responded with a discharge. The orthodromic latencies of unitary discharges ranged from 1.1 to 4.4 ms to stimulation of the dorsolateral funiculus, and from 1.1 to 4.9 ms to stimulation of the dorsal columns. Most responses are likely to be monosynaptic. Differences in latencies were not associated with location of recording sites or thalamic projection sites of nucleus Z neurons. 5. The responsiveness of many neurons (n = 84) was tested to natural stimulation of the ipsilateral hindlimb (which provides the sensory input to nucleus Z).(ABSTRACT TRUNCATED AT 400 WORDS)

Dorsal column input to thalamic VL neurons: an intracellular study in the cat.

This study investigated the role of the ventral lateral (VL) nucleus of the thalamus as a lemniscal relay to motor cortex. Intracellular recordings were obtained from thalamic VL relay neurons in cats anesthetized with chloralose, following stimulation of the dorsal column nuclei. VL neurons were identified by their short-latency input from the cerebellar nuclei, their antidromic activation from motor cortex and their anatomical location. A total of 105 neurons was studied. The occurrence of temporal facilitation to double volleys was also examined. It was found that 80/105 (75%) neurons responded with excitation and/or inhibition to stimulation of the dorsal column nuclei. The latencies of the postsynaptic responses ranged from 2.0 to 20 ms (median 10.0 ms). The latencies of nearly all responses (79/80) were greater than 3 ms and nearly all responses (45/47) which were tested for it, displayed temporal facilitation to double shock stimulation, consistent with polysynaptic transmission. Effective stimulation sites were found in the gracile and cuneate nuclei. Recording sites were located throughout VL, including the "border region" with the ventral posterior lateral nucleus (VPL). There was no obvious topographic relationship between location of recording site and latency or polarity (excitation versus inhibition) of the synaptic responses. This is consistent with dorsal column input diffusely distributed over VL. When the recording electrodes penetrated VPL, characteristics of the EPSPs were indicative of monosynaptic transmission (short latency, no temporal facilitation). This clear transition from VL to VPL suggests that it is not necessary to define, on physiological grounds, a separate "border region" between these two nuclei.(ABSTRACT TRUNCATED AT 250 WORDS)