Developmental changes in the susceptibility to long-term potentiation of neurones in rat visual cortex slices.

We investigated with intracellular recordings from rat visual cortex slices whether the susceptibility to undergo long-term potentiation (LTP) is age-dependent and whether it is correlated with the expression of synaptic responses mediated by N-methyl-D-aspartate (NMDA) receptors. Test and tetanic stimuli were applied to the white matter and post-tetanic modifications of the amplitude of postsynaptic potentials (PSPs) were assessed in regular spiking cells of supragranular layers. At 2 weeks of age, the amplitudes of early (8-10 ms post-stimulus) and late (20 ms post-stimulus) PSP-components increased after tetanic stimulation to 137.1 +/- 13.4% and 141.3 +/- 12.1% of the pretetanic controls, respectively. At 3 weeks, potentiation of both PSP-components was less pronounced but still significant, the late component being on average more potentiated than the early one. At 4 weeks, PSPs were no longer potentiated. Bath application of 25 microM DL-2-amino-5-phosphonovalerate (APV), an NMDA receptor antagonist, blocked LTP induction both at 2 and at 3 weeks. We also studied developmental changes of two synaptic responses known to influence the susceptibility of cortical neurones to LTP, the NMDA receptor-mediated excitatory PSP (EPSP) and the initial inhibitory PSP (iIPSP). The amplitude of the APV-sensitive EPSP decreased with age and reached adult values in 4-week-old animals. The iIPSPs were pronounced already at 2 weeks and showed no marked change during further development. The results suggest a close correlation between the susceptibility to undergo LTP and the extent to which NMDA receptor-gated conductances contribute to the synaptic response.(ABSTRACT TRUNCATED AT 250 WORDS)     

Rapadilino syndrome

We report on a boy with severe radial hypoplasia, absent thumbs and patellae, short stature, persistent diarrhea, slender nose and normal intelligence as another example of the RAPADILINO syndrome. © 1992 Wiley-Liss, Inc.     

Fetal dexamethasone exposure affects basal ornithine decarboxylase activity in developing rat brain regions and alters acute responses to hypoxia and maternal separation

Although glucocorticoids are widely used to stimulate fetal/neonatal lung function, they also interfere with cellular development in the central nervous system. Dexamethasone was administered to pregnant rats in late gestation at a dose (0.8 mg/kg) that lies just above the threshold for stimulation of lung surfactant synthesis, and the impact on ornithine decarboxylase (ODC) was evaluated in three brain regions. Dexamethasone treatment produced an initial inhibition of basal ODC activity followed by postnatal elevations, a pattern known to be associated with delays in cell replication and differentiation. Dexamethasone also interfered with the ability of the 1-day-old neonate to turn off ODC acutely in response to a 2-h period of maternal separation; as this response conserves energy in the absence of the dam, the effect of dexamethasone is maladaptive. Additionally, dexamethasone sensitized the neonatal brain to hypoxia: the acute increase of ODC associated with a 2-h exposure to 7% O2 was exacerbated in 8-day-old rats exposed to dexamethasone prenatally. These results suggest that administration of dexamethasone, in doses that promote respiratory competence, delays cell development in the central nervous system and renders the brain more vulnerable to adverse neonatal conditions, such as maternal separation or hypoxia.     

CRITERIA ADOPTED BY DENTISTS TO INDICATE THE EXTRACTION OF PERIODONTALLY INVOLVED TEETH

When dealing with patients with periodontal disease of variable severities, dentists must often choose between treating and restoring the involved tooth or indicating its extraction. Different criteria have been adopted in this decision-making process. The purpose of this study was to evaluate the criteria adopted by dentists to indicate the extraction of teeth with periodontitis. Dentists were interviewed at their private practices in three cities of the state of Rio Grande do Sul, Brazil. The evaluated criteria included severity of attachment loss, tooth mobility, furcation involvement, prosthetic planning, periodontal-endodontic lesion, possible systemic involvement due to the presence of periodontitis, referral to a periodontist for evaluation, radiographic bone loss greater than 50%, presence of extensive caries, socio-economic and cultural status of the patient, among others. The most often adopted criteria to indicate the extraction of periodontally affected teeth were the presence of mobility (37.5%), severity of attachment loss (24.3%) and radiographic bone loss greater than 50% (21.2%). The results of the present study demonstrated the difficulties faced by dentists to indicate the extraction of teeth with severe attachment loss, in addition to the establishment of an adequate prognosis. Aspects associated with the past disease were still the most often reported to indicate the extraction of teeth for periodontal reasons.     

The fillet foot for endweight-bearing cover of below knee amputations

Four patients with five severely traumatized lower legs but preserved feet were treated with fillet flaps from the foot to cover an elective, below knee amputation stump. The posterior tibial neurovascular bundle nourished and innervated this flap. While the posterior tibial artery and vein may be cut and re-anastomosed to prevent kinking and occlusion, the posterior tibial nerve should always be kept in continuity to maintain the quality of sensation to this flap. Four flaps survived and one necrosed secondary to venous insufficiency. Due to its innervation and the unique qualities of heel skin, the flap is very durable and has endweight-bearing capabilities. This has permitted the fitting of an endweight-bearing, total contact, fully extended, below knee prosthesis that appears to offer significant improvement in ease of use and normality of gait pattern over standard patellar tendon-bearing prostheses.     

Evidence of Increased Class I MHC Expression on Human Peripheral Blood Lymphocytes during Acute Ethanol Intoxication

Certain ethanol-related diseases in humans have been linked to disorders of immunity. Although humoral and cellular immunity have been studied, the precise mechanisms whereby ethanol use leads to tissue damage remain unknown. In order to explore the hypothesis that ethanol may lead to alteration in expression of tissue Class I major histocompatibility antigen causing an autoimmune phenomenon, a population of acutely ethanol-intoxicated patients was studied. Measurement of Class I major histocompatibility antigen on peripheral blood lymphocytes in this population showed a highly significant (p less than 0.01) increase over controls. The role that this increased antigenicity may play in the evolution of clinical disease is discussed.     

Periodic lateralized epileptiform discharges: etiology, clinical aspects, seizures, and evolution in 130 patients.

The purpose of this study was to analyze the clinical aspects in 130 patients presenting periodic lateralized epileptiform discharges (PLEDs) in their EEG and to compare these results with those found in the literature. Etiology, neurologic deficit, seizure occurrence, and evolution were studied in each patient by historical review. The recordings were obtained on 8- or 16-channel EEGs with electrode placement according to the International 10-20 System. Recordings containing PLEDs were selected. PLEDs were defined as repetitive periodic, focal, or hemispheric epileptiform discharges (spikes, spike and waves, polyspikes, sharp waves) usually recurring every 1 to 2 seconds. The statistical study was carried out via the chi(2) test using the computer program SPSS. The main etiology found in this group of patients was stroke (61 of 130 patients). Other processes found were brain infections, tumors, hematomas, and several other entities grouped together as miscellaneous (anoxic encephalopathy, subarachnoid hemorrhage, craniocerebral trauma, Creutzfeldt-Jacob disease, migraine, multiple sclerosis, and aminophylline intoxication). Half of these patients (65 of 130) developed seizures, mostly partial motor seizures. No significant relation between etiology and seizures was found (chi(2) = 2.81, P = 0.4222). Seizures recurred in 14 of 130 patients during a follow-up of 14.5 months. PLEDs were not recorded in any EEG at the time of seizure recurrence. PLEDs constitute a distinctive but uncommon EEG phenomenon of repetitive, periodic, and stereotyped lateralized complexes. In agreement with the literature, PLEDs were associated with an acute process and occurred early during the course of the illness in all patients studied and were usually associated with structural lesions, with stroke being the main etiology. Traditionally, seizures occur with PLEDs but it is also accepted that they can exist in patients who never develop epileptic activity, either clinically or electrically, as demonstrated in 50% of the patients studied. No significant association between seizures and any etiology could be found. It was not demonstrated that the occurrence of seizures may influence the outcome in any way.