Macrodontia associated with growth-hormone therapy: a case report and review of the literature.

BACKGROUND: Macrodontia is a rare dental anomaly, and isolated macrodontia is even more infrequent. The aim of this article is to report on a young male patient with macrodontia of the mandibular premolars. CASE REPORT: We herein present a case report of a young male patient receiving pharmacological growth hormone therapy for 10 years, who was diagnosed with macrodontia of the mandibular premolars. The patient underwent surgical treatment at the School of Dentistry of the University of Buenos Aires and was followed-up for more than 3 years. CONCLUSION: Macrodontia is a rare condition. Early diagnosis and treatment of this anomaly favors adequate formation of the dental arches. In the light of this case report, a review of paediatric patients who received growth hormone therapy during the tooth formation stage would seem relevant.

Thin-film micro-electrode stimulation of the cochlea in rats exposed to aminoglycoside induced hearing loss.

The multi-channel cochlear implant (CI) provides sound and speech perception to thousands of individuals who would otherwise be deaf. Broad activation of auditory nerve fibres when using a CI results in poor frequency discrimination. The CI also provides users with poor amplitude perception due to elicitation of a narrow dynamic range. Provision of more discrete frequency perception and a greater control over amplitude may allow users to better distinguish speech in noise and to segregate sound sources. In this research, thin-film (TF) high density micro-electrode arrays and conventional platinum ring electrode arrays were used to stimulate the cochlea of rats administered sensorineural hearing loss (SNHL) via ototoxic insult, with neural responses taken at 434 multiunit clusters in the central nucleus of the inferior colliculus (CIC). Threshold, dynamic range and broadness of response were used to compare electrode arrays. A stronger current was required to elicit CIC threshold when using the TF array compared to the platinum ring electrode array. TF stimulation also elicited a narrower dynamic range than the PR counterpart. However, monopolar stimulation using the TF array produced more localised CIC responses than other stimulation strategies. These results suggest that individuals with SNHL could benefit from micro stimulation of the cochlea using a monopolar configuration which may provide discrete frequency perception when using TF electrode arrays.

Modulation of medial geniculate nucleus neuronal activity by electrical stimulation of the nucleus accumbens.

Dysfunctional sensory gating has been proposed to result in the generation of phantom perceptions. In agreement, it has been recently suggested that tinnitus, a phantom perception of sound commonly associated with hearing loss, is the result of a breakdown of circuitry involving the limbic system and the medial geniculate nucleus (MGN) of the thalamus. In humans with tinnitus, structural changes and abnormal activity have been found to occur in the auditory pathway as well as parts of the limbic system such as the nucleus accumbens (NAc). However, at present, no studies have been conducted on the influence of the NAc on the MGN. We investigated the functional connectivity between the NAc and MGN single neurons. Bipolar electrical stimulation was delivered to the NAc while recording single neuron activity in MGN in anesthetized Wistar rats. Histological analysis was used to confirm placement of electrodes. NAc electrical stimulation generally decreased spontaneous firing rates in MGN neurons and, in a limited number of neurons, caused an increase in firing rate. This suggests that NAc can modulate the activity of auditory neurons in the MGN and may play a role in the development of tinnitus.

Intralaminar stimulation of the inferior colliculus facilitates frequency-specific activation in the auditory cortex.

OBJECTIVE: Auditory midbrain implants (AMI) provide inadequate frequency discrimination for open set speech perception. AMIs that can take advantage of the tonotopic laminar of the midbrain may be able to better deliver frequency specific perception and lead to enhanced performance. Stimulation strategies that best elicit frequency specific activity need to be identified. This research examined the characteristic frequency (CF) relationship between regions of the auditory cortex (AC), in response to stimulated regions of the inferior colliculus (IC), comparing monopolar, and intralaminar bipolar electrical stimulation. APPROACH: Electrical stimulation using multi-channel micro-electrode arrays in the IC was used to elicit AC responses in anaesthetized male hooded Wistar rats. The rate of activity in AC regions with CFs within 3 kHz (CF-aligned) and unaligned CFs was used to assess the frequency specificity of responses. MAIN RESULTS: Both monopolar and bipolar IC stimulation led to CF-aligned neural activity in the AC. Altering the distance between the stimulation and reference electrodes in the IC led to changes in both threshold and dynamic range, with bipolar stimulation with 400 µm spacing evoking the lowest AC threshold and widest dynamic range. At saturation, bipolar stimulation elicited a significantly higher mean spike count in the AC at CF-aligned areas than at CF-unaligned areas when electrode spacing was 400 µm or less. Bipolar stimulation using electrode spacing of 400 µm or less also elicited a higher rate of elicited activity in the AC in both CF-aligned and CF-unaligned regions than monopolar stimulation. When electrodes were spaced 600 µm apart no benefit over monopolar stimulation was observed. Furthermore, monopolar stimulation of the external cortex of the IC resulted in more localized frequency responses than bipolar stimulation when stimulation and reference sites were 200 µm apart. SIGNIFICANCE: These findings have implications for the future development of AMI, as a bipolar stimulation strategy may improve the ability of implant users to discriminate between frequencies.

Midbrain responses to micro-stimulation of the cochlea using high density thin-film arrays.

A broader activation of auditory nerve fibres than normal using a cochlear implant contributes to poor frequency discrimination. As cochlear implants also deliver a restricted dynamic range, this hinders the ability to segregate sound sources. Better frequency coding and control over amplitude may be achieved by limiting current spread during electrical stimulation of the cochlea and positioning electrodes closer to the modiolus. Thin-film high density microelectrode arrays and conventional platinum ring electrode arrays were used to stimulate the cochlea of urethane-anaesthetized rats and responses compared. Neurophysiological recordings were taken at 197 multi-unit clusters in the central nucleus of the inferior colliculus (CIC), a site that receives direct monaural innervation from the cochlear nucleus. CIC responses to both the platinum ring and high density electrodes were recorded and differences in activity to changes in stimulation intensity, thresholds and frequency coding of neural activation were examined. The high density electrode array elicited less CIC activity at nonspecific frequency regions than the platinum ring electrode array. The high density electrode array produced significantly lower thresholds and larger dynamic ranges than the platinum ring electrode array when positioned close to the modiolus. These results suggest that a higher density of stimulation sites on electrodes that effectively 'aim' current, combined with placement closer to the modiolus would permit finer control over charge delivery. This may equate to improved frequency specific perception and control over amplitude when using future cochlear implant devices.

Adapting EVIAVE methodology as a planning and decision-making tool in Venezuela.

Landfills in Venezuela have serious problems regarding their location, design and operation. In fact, basic waste disposal is one of the main weaknesses of the municipal waste management in this country. The Venezuelan Ministry of Environment and Renewable Resources has studied and identified the negative impacts of operating landfills, but no program has been implemented to determine the cause-effect relation of these impacts or to design strategies to counteract with the serious environmental and health risks generated. This paper describes how EVIAVE methodology can be successfully used for landfill diagnosis, and shows how this type of landfill diagnosis was applied in Venezuela. For our research study, we carried out both a quantitative and qualitative evaluation of the environmental problems generated by 22 landfills in Venezuela. Our study was based on the following environmental indexes: Landfill Environment, Environmental Risk, Environmental Value, and Probability of Contamination. For the purposes of our study, it was first necessary to adapt EVIAVE to the legal system and social context in Venezuela. The results obtained confirmed the applicability of this methodology to Venezuelan landfills. EVIAVE was found to be an effective planning tool that provided crucial information for the development of action plans, which would improve landfill operation, and help make decisions pertaining to their closure, sealing and eventual recovery.

Synaptic responses in cochlear nucleus neurons evoked by activation of the olivocochlear system.

The action of olivocochlear collaterals to the cochlear nucleus is not fully established. Synaptic ultrastructure suggests an excitatory role. Extracellular recordings show spikes evoked by electrical stimulation of olivocochlear axons, but these spikes in the cochlear nucleus may be antidromic (activation of output axons) or orthodromic (synaptic input). We therefore recorded intracellular responses to shocks to olivocochlear axons in anaesthetized guinea pigs. In chopper and primary-like neurons shocks caused either no response or an inhibitory synaptic response (IPSP), but never an excitatory one (EPSP). In contrast, onset neurons never showed IPSPs but showed a variety of other responses; antidromic spikes, EPSPs, orthodromic spikes or no effect. The results agree with earlier extracellular observations in that olivocochlear collaterals provide excitatory input to onset neurons. Because some onset neurons are inhibitory they may be the source of the IPSPs observed in other cochlear nucleus neurons. The data also show that electrical stimulation at the floor of the IVth ventricle results in antidromic spikes as well. However, intracellular recording enabled the orthodromic action to be verified and the presumed olivocochlear action to be better understood. Our data support the hypothesis that olivocochlear collaterals initiate excitatory input onto onset-chopper neurons.

Physical-mechanical and environmental properties of sintered municipal incinerator fly ash.

A step-wise treatment of Municipal Solid Waste (MSW) incinerator fly ash including washing, milling and sintering was investigated in order to manufacture ceramic materials with improved physical, mechanical and environmental properties and, possibly, to reduce the power input of the sintering process. An interpretation of the test results based on the microstructure of sintered products and sintering kinetic modeling was also attempted to identify the densification mechanisms. It was found that milling of washed fly ash represents a basic step for manufacturing high-density ceramic materials with very high compressive strengths (up to 500 N/mm2). A significant reduction in the power input of the sintering process (reduction of firing temperature from 1210 degrees C for washed fly ash to 1140 degrees C for milled-washed fly ash) is also achieved. A dense, well-sintered microstructure is formed through an intermediate-stage, liquid-phase sintering mechanism controlled by liquid-phase diffusion and grain shape accommodation. Such a microstructure is able to strongly immobilise heavy metals, thus giving good environmental properties to sintered product.

[Some behavioral characteristics of physicians desired by ambulatory patients. A pilot survey]. / Alcune caratteristiche comportamentali del medico desiderate dal paziente in ambito ambulatoriale. Indagine conoscitiva pilota.

AIMS: We must pay attention to character formation of Medical Doctors because it could build a good or bad relationship with colleagues and patients: it is not a merely "humanistic" goal but a necessary component of professional excellence. The first endpoint of this study is to identify how to improve the quality of the outpatient visit. MATERIALS AND METHODS: We tested a user-friendly questionnaire, distributed to 100 patients. RESULTS AND CONCLUSIONS: The most important behavioral characteristics desired by patients from physicians are: 1. to have the physician's attention without feeling hurried (such as without the physician answering a phone call during the office visit); 2. to have continuity of care even in the ambulatory setting; 3. to find a relationship of empathy, participation and sharing; 4. to have a peaceful relationship of collaboration with the nurses and other health care personnel; 5. to find the physician appropriately groomed and dressed; 6. to receive the full diagnosis with clarity and at the most appropriate moment of communication.

Use of histopathological indicators on chub (Leuciscus cephalus) and brown trout (Salmo trutta fario) in evaluating river environments.

A multidisciplinary study was conducted on water from two rivers in the Abruzzo region of Italy. The study highlighted the importance of histopathological investigations in the evaluation of the environmental impact on fish. Brown trout (Salmo trutta fario) from the Aterno river and chub (Leuciscus cephalus) from the Vomano river were sampled in winter and then again in spring. Histopathological investigations of gills, kidneys and livers revealed inflammatory and degenerative lesions, early warning signals of environmental stress. Lesions were evaluated semi-quantitatively and findings were ranked. The histopathological features were compared with results obtained from the analysis of water samples and macroinvertebrates collected in the two rivers (extended biotic index). All results confirmed alterations of the environment.

Vaccination trials of sea bass (Dicentrarchus labrax) against pasteurellosis using oral, intraperitoneal and immersion methods.

Photobacterium damsela subsp. piscicida (Phdp) is the aetiological agent of fish pasteurellosis, causing heavy losses in intensive mariculture plants. The present work compares the protective efficacy of five different vaccine formulation: oral, intraperitoneal, immersion, bivalent immersion (Vibrio anguillarum) and immersion associated with immunostimulants. Each of these vaccine formulations containing whole cells of Phdp formalin inactivated (FKC), was administered to 100 sea bass weighing approximately 2 g; 100 non-vaccinated sea bass were used as controls. Protection against pasteurellosis was tested for 40 days after vaccination by intraperitoneal challenge: each fish was inoculated with Phdp cells at a concentration of 2.75 x 10(4) cfu/ml. Mortality was recorded over the following 14 days, vaccine protection was evaluated using a relative percentage survival (RPS) index. The intraperitoneal formulation gave excellent protection (RPS 82.4%). The most effective immersion form was that followed by simple immersion (RPS 23.1%) followed by the group vaccinated with bivalent vaccine (RPS 18.7%). Protection conferred orally (RPS 28.6%) is of interest for practical purposes.

[Predisposing factors for development of cardial adenocarcinoma]. / Fattori predisponenti l'adenocarcinoma del cardias.

After a careful revision of the various papers and on the basis of their personal experience, the persons responsible for this project analyse the factors that, today, influence the development of an adenocarcinoma in the region of the gastro-esophageal junction. They also study therapeutic strategies on the basis of new findings in anatomic-physiological matters of this region. From this analysis, specialists notice an increase in adenocarcinomas which affect the gastric region of the cardia, in comparison with carcinomas which affects the gastric region in toto. By considering Barrett, Hayward, Riedel and Ruol's studies, they maintain that the fundamental factor which causes the development of cardial adenocarcinoma is the gastroesophageal reflux. This reflux acts as a chronic irritative stimulus on the esophageal wall and therefore it provokes an increase in mucous secretion and the formation of metaplasia. This metaplasia is initially mucosecreting, acid-secreting and in the end it becomes intestinal. This also leads to the appearance of absorbent calciform cells; the absorption of toxic or mutagenic substance for the cell itself, will be the next step for the development of an adenocarcinoma. Nowadays the therapy of intestinal metaplasia provides for different therapeutic levels: from the endoscopic monitoring (which is used for the most serious cases of dysplasia), to the PPI medical treatment(today in disuse), to the surgical laparoscopic treatment with non-refluxing plasty (Nissen, Toupet). This last treatment is today associated with endoscopic esophageal mucosectomy in order to achieve a better effectiveness. This happens through the use of various methodologies, for example the multipolar electrocoagulation.

Olivocochlear collaterals evoke excitatory effects in onset neurones of the rat cochlear nucleus.

Axons of medial olivocochlear neurones in the superior olivary complex terminate on the outer hair cells of the cochlea and also give off collaterals that terminate in the cochlear nucleus. Previous work in our laboratory, using extracellular recordings in the cochlear nucleus, has indicated that stimulation of the olivocochlear axons may have an excitatory effect on specific cell populations of the cochlear nucleus, such as onset-choppers, in contrast to the peripheral suppressive action of the same axons. We have investigated whether this excitation is produced by action of the olivocochlear collaterals in the cochlear nucleus or whether it is mediated via the peripheral suppression, by measuring intracellular responses in the rat cochlear nucleus to electrical stimulation of the olivocochlear axons in silence. The results demonstrate that single shocks applied to the olivocochlear axons can evoke excitatory postsynaptic potentials in onset neurones. We observed an inhibitory effect in one chopper only. In the same animals in all other neurones investigated (i.e. three primary-like neurones and eight choppers) the same stimulation was without any effect on cell membrane potential. We conclude that the excitatory effects in onset neurones are not caused by suppression in the auditory peripheral organ, but by activation of olivocochlear collaterals in the cochlear nucleus.

Lymph node dissection in surgical treatment of esophageal neoplasms.

BACKGROUND: Until now therapy of carcinoma of the esophagus has presented an aura of pessimism, resulting in an attitude among physicians that cure was impossible. Presently the overall 5-year survival is between 38.3% and 55% thanks to new radical surgical techniques. The aim of this work is to evaluate lymph node dissection in treatment of esophageal carcinoma by analyzing morbidity, mortality, survival and quality of life. METHODS: From 1975 to 1995, 170 patients with carcinoma of the esophagus and cardia underwent operation, of whom 165 underwent 2-field lymphadenectomy and four 3-field lymphadenectomy; one patient was submitted to self-transplanting jejunal loop to neck. One hundred and twenty-two patients had standard resection and 47 en bloc resection. RESULTS: Lymph node involvement is often found in patients with superficial carcinoma and it greatly influences outcome after esophagectomy. In 2-field lymphadenectomy morbidity and mortality are more frequent in en bloc resections; global 3-year survival was better in patients with early lesions. Three-field lymphadenectomy was performed in only few cases, not sufficient to express a definitive opinion. CONCLUSIONS: On the basis of our experience, we conclude that the better survival is particularly dependent on early diagnosis, histological type of neoplasia and following surgical treatment, especially on the type of resection with 2 or 3-field lymphadenectomy.

Delay analysis in the auditory brainstem of the rat: comparison with click latency.

Many cells in the auditory brainstem 'phase lock' to tone stimuli. From the changing phase relationship between the stimulus and the neural response in phase-locking cells, the delay between them can be estimated. This delay, however, is consistently greater than the latency measured in response to click stimuli, an important discrepancy. In this paper the different measures of delay, namely phase delay, group delay and signal-front delay are re-examined. An improved method for computing the average group delay is presented, which accounts for the cyclical nature of the phase data. Data were collected from units in successive processing sites of auditory pathway: the auditory nerve, the cochlear nucleus, the trapezoid body and the medial nucleus of the trapezoid body. Low-characteristic frequency (CF) units gave multimodal post-stimulus-time histograms in response to clicks, and showed stepwise decreases in latency with increasing intensity, with the appearance of earlier peaks in the response, rather than shifts in the timing of the peaks. The separation of peaks corresponded to the inverse of the unit's CF. High-CF units also showed a decline in click latency with intensity, but to a lesser degree than low CF units. We present an analysis which explains the difference between click latency and delay, and which in contrast to previous accounts is experimentally testable. We demonstrate that this new framework accounts for the discrepancy between the two measures of delay, and in addition accounts for the observed stepwise shifts in click latency for low-CF units.

Temporal processing from the auditory nerve to the medial nucleus of the trapezoid body in the rat.

This investigation examines temporal processing through successive sites in the rat auditory pathway: auditory nerve (AN), anteroventral cochlear nucleus (AVCN) and the medial nucleus of the trapezoid body (MNTB). The degree of phase-locking, measured as vector strength, varied with intensity relative to the cell's threshold, and saturated at a value that depended upon stimulus frequency. A typical pattern showed decline in the saturated vector strength from approximately 0.8 at 400 Hz to about 0.3 at 2000 Hz, with similar profiles in units with a range of characteristic frequencies (480-32,000 Hz). A new expression for temporal dispersion indicates that this variation corresponds to a limiting degree of temporal imprecision, which is relatively consistent between different cells. From AN to AVCN, an increase in vector strength was seen for frequencies below 1000 Hz. At higher frequencies, a decrease in vector strength was observed. From AVCN to MNTB a tendency for temporal coding to be improved below 800 Hz and degraded further above 1500 Hz was seen. This change in temporal processing ability could be attributed to units classified as primary-like with notch (PL(N)). PL(N) MNTB units showed a similar vector strength distribution to PL(N) AVCN units. Our results suggest that AVCN PL(N) units, representing globular bushy cells, are specialised for enhancing the temporal code at low frequencies and relaying this information to principal cells of the MNTB.