Search PubMed⌕ Search

Biomedical subjects

A Giovanni

Publications and source records attributed to A Giovanni.

At least 91 records · Page 5Linked to original sources
PubMed1992

[How to evaluate velar insufficiency?].

The evaluation of velar insufficiency is absolutely necessary in order to assess the results of surgery of the labial palatal cleft. In addition to the clinical examination which remains indispensable, the aerophonometer, applicable to adults and children as from the age of 3, enables simultaneous measurement of the flow of buccal air, the flow of nasal air, and the buccal phonogram. The comparison of the lines, the relation of the nasal air and buccal air flows, upon the emission of two standard sentences with and without nasal components, enables an objective assessment of velar functioning.

Child, Preschool↗
PubMed1992

[A multiparameter method of computer-assisted objective vocal evaluation].

The aim of this study is to validate an aid for the evaluation of dysphonia with objective measurements. We recorded exhaled airflow, fundamental frequency and sound level pressure, for a sustained vowel "a", with 51 dysphonic subjects and 15 normal subjects. The following measurements are made on these three parameters: mean value, standard deviation and coefficient of variation. The exhaled airflow volume was also computed for a duration of 2 seconds. A principal components analysis of the measurements indicated that it is possible to recognise the classes of vocal evaluation and vocal pathology. These findings reinforce on objective aid for the vocal evaluation of dysphonia.

Diagnosis, Computer-Assisted↗
PubMed1991

Correlation between the neostriatal content of the 1-methyl-4-phenylpyridinium species and dopaminergic neurotoxicity following 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration to several strains of mice.

In the present study we observed pronounced differences in the capacity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to induce dopaminergic neurotoxicity in several strains of mice. For example, there was no MPTP-induced decrement in neostriatal dopamine content in Ace Swiss-Webster mice and a 92% decrement in Taconic Farms C57 bl mice. Several parameters which could possibly explain this differential sensitivity to MPTP were studied. These include: 1) neostriatal monoamine oxidase-B (MAO-B) activity; 2) the capacity of neostriatal synaptosomes prepared from the mouse strains to accumulate 1-methyl-4-phenylpyridinium (MPP+), the major metabolite of MPTP formed via oxidation by MAO-B; and 3) the neostriatal MPP+ content after MPTP administration to the mice. There were no significant differences in the Km values for MAO-B in the neostriatum among the strains of mice examined. Neostriatal Vmax values for MAO-B differed somewhat among the strains, with a low of 2915 +/- 172 nmol/g of tissue per hr (CD-1 mice from Charles River) and a high of 3884 +/- 203 nmol/g of tissue per hr (C57 bl mice from Taconic Farms). However, Vmax values for MAO-B in the mouse strains did not correlate significantly with the relative sensitivity of the strains to MPTP. There were no significant differences in the capacity of neostriatal synaptosomes prepared from the mouse strains to accumulate MPP+. Studies on the metabolism of MPTP after peripheral administration revealed that there was a significant (P less than .01) positive correlation between the relative sensitivity of the mouse strains to MPTP and their neostriatal MPP+ content after MPTP administration.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1990

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine- and 1-methyl-4-(2'-ethylphenyl)-1,2,3,6-tetrahydropyridine-induced toxicity in PC12 cells: role of monoamine oxidase A.

The toxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 1-methyl-4-(2'-ethylphenyl)-1,2,3,6-tetrahydropyridine (2'Et-MPTP), and their corresponding pyridinium species was studied in the rat pheochromocytoma PC12 cell line. MPTP and its analogues are known to be metabolized by monoamine oxidase (MAO) to dihydropyridinium intermediates which are further transformed, either enzymatically or spontaneously, into pyridinium species. MAO activity in PC12 cells is almost exclusively of the A form, and 2'Et-MPTP is a good substrate for both MAO-A and MAO-B. In contrast, MPTP is a poor substrate for MAO-A, but a good substrate for MAO-B. 2'Et-MPTP caused considerably more cell death than MPTP in the PC12 cells. However, 1-methyl-4-(2'-ethylphenyl)pyridinium and 1-methyl-4-phenylpyridinium, the corresponding pyridinium species formed from 2'Et-MPTP and MPTP, respectively, were equipotent as toxins. The toxic effects of the tetrahydropyridines and their corresponding pyridiniums were both concentration- and time-dependent. Measurements of the levels of the pyridinium species formed and the remaining tetrahydropyridine in the media indicated that 2'Et-MPTP was converted about five to seven times more readily into its toxic pyridinium species than was MPTP. There was, moreover, an excellent correlation between amount of pyridinium formed and cell death. There was also a parallel between the capacity of clorgyline and pargyline, irreversible MAO inhibitors, to decrease the formation of the pyridinium species and their capacity to protect against the toxic actions of the tetrahydropyridines. These data are consistent with the concept that the MAO-A-dependent formation of the pyridinium species from the tetrahydropyridine is a prerequisite for toxicity in PC12 cells.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1990

[Treatment of laryngotracheal stenoses in children].

Over a period of 5 years, from 1984 to 1989, 35 children were treated surgically for a laryngo-tracheal stenosis, 27 by an external approach, 8 by endoscopy with the CO2 laser. Of the children, 25 (71%) were under 5 years old at the time of treatment and 77% of the stenoses (n = 27) corresponded to a post-intubation and/or tracheotomy acquired etiology. Based on the classification of stenoses according to the extent of the impairment of the aerial lumen, the authors stress the value of conservative treatment (endoscopy) in Stage I (less than 70%, n = 8), and of treatment using the external approach in Stage II (between 70% and 90%, n = 12), in Stage III (between 90% and 99%, n = 12) and Stage IV (complete obstruction, n = 3). The technique most widely used currently is laryngo-tracheoplasty with the insertion of costal cartilage (n = 17). Analysis of the results shows that decannulation was successful in 85% of the cases. With respect to the management of stenoses in the new-born baby, the authors report on their recent experience with laryngo-trachoe-fissure in 6 cases as an alternative either to tracheotomy in difficult extubations, or to laryngo-tracheoplasty when the child's weight is particularly low.

Adolescent↗
PubMed1988

Studies with the neurotoxicant 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and several of its analogs.

The nigrostriatal dopaminergic neurotoxicity of MPTP was prevented in mice in a dose-dependent manner by the monoamine oxidase-B (MAO-B) inhibitor deprenyl. This finding, combined with other observations, points out the important role of MAO-B in the bioactivation of MPTP. In the present study, some comparisons between MPTP and several of its structural analogs will be presented.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1988

Importance of monoamine oxidase A in the bioactivation of neurotoxic analogs of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a potent dopaminergic neurotoxin that causes biochemical, pharmacological, and pathological deficits in experimental animals similar to those seen in human parkinsonian patients. All of the deficits can be prevented by treating mice with selective inhibitors of monoamine oxidase B (MAO-B), including deprenyl, prior to MPTP administration. We now report that the dopaminergic neurotoxicity of two potent MPTP analogs, namely the 2'-methyl and 2'-ethyl derivatives (2'-MeMPTP and 2'-EtMPTP), cannot be prevented by deprenyl pretreatment. However, the neurotoxicity of these two analogs can be prevented by pretreatment with a combination of deprenyl and the selective MAO-A inhibitor clorgyline at doses that are sufficient to almost completely inhibit both MAO-B and MAO-A activities. Moreover, the neurotoxicity of 2'-EtMPTP (but not of 2'-MeMPTP and MPTP) can be significantly attenuated by clorgyline alone. There was a parallel between the capacity of the MAO inhibitors to decrease the brain content of the pyridinium species after administration of the tetrahydropyridines and the capacity of the MAO inhibitors to protect against the neurotoxic action of the tetrahydropyridines. The data support the conclusion that both 2'-MeMPTP and 2'-EtMPTP are bioactivated to pyridinium species to a significant extent by MAO-A. Further, it appears that the formation of the pyridinium species plays an important role in the neurotoxic process.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1988

[Contribution of nuclear magnetic resonance in the neuro-otologic diagnosis of acoustic neuroma. Screening and evaluation of its extension].

Forty patients with suspected tumoral syndrome of ponto-cerebellar angle were investigated by NMR imaging. The method proved to be reliable, less invasive (lack of irritation and absence of iodized contrast) and as rapid as CT scan imaging for the diagnosis of presence and extension of an VIIIth nerve neurinoma. It also allowed avoidance of computerized gas meatography during screening for intracanal neurinomas.

Audiometry↗
PubMed1986

[Requisite selection of surgical technics in the treatment of cancer of the larynx].

Rules for functional surgery of cancer of larynx are defined by means of a detaited analysis of results of 43 cases of reconstructive anterior frontal laryngectomy, 17 cases of crico-hyoide-epiglottopexy and 32 cases of crico-hyoidopexy. The carcinologic features of this surgery are discussed, and emphasis placed on the importance of the paraglottic space and its functional conditions in the light of recent physiologic data. Surgical procedures used are outlined with, for each of them, the neoplastic localization suitable for treatment and a critical analysis of postoperative functional results. Carcinologic follow up is still insufficient for several techniques used, preventing any precise conclusions to be drawn, but the authors consider it is justifiable to perform 66% of partial as against 34% of total laryngectomies.

Humans↗
PubMedDate not supplied

Near total laryngectomy with epiglottic reconstruction: long-term results in 57 patients.

INTRODUCTION: Extended partial laryngectomy procedures may offer patients the potential for a cure with preservation of voice. This report characterizes our patients managed with near laryngectomy and reconstructed with epiglottic tissue. MATERIALS AND METHODS: A total of 57 patients with T1 or T2 glottic carcinoma undergoing total laryngectomy with epiglottic reconstruction were reviewed retrospectively. This group included 15 patients with T1 lesions and 42 patients with T2 lesions. In the standard operation the specimen includes the thyroid ala, both vocal cords, both false vocal cords, and one arytenoid cartilage. The epiglottis is mobilized and delivered inferiorly for reconstruction of the glottic larynx. RESULT: Tumor control was obtained in 93% of T1 patients and 79% of T2 patients. All patients tolerated decannulation. After a mean duration of 12 days (range 5 to 22 days), all patients were able to swallow. Voice evaluation revealed 5 patients had whispery voices, 25 were difficult to understand in a noisy environment, and 27 were easily understood. DISCUSSION: This technique is an effective approach to cancer therapy with cure rates comparable to total laryngectomy. The main limitation of this technique is that voice recovery is unpredictable.

Deglutition↗
PubMedDate not supplied

Cell cycle regulators in neuronal death evoked by excitotoxic stress: implications for neurodegeneration and its treatment.

Excitotoxic stress is potentially an important component of disorders such as stroke and neurodegenerative diseases. Its toxic effects appear to be transduced through mechanisms that result in both acute and delayed forms of death. We examined here whether cyclin dependent kinases (CDKs), molecules normally associated with cell cycle control, may be involved in delayed excitotoxic death in two different excitotoxin models. We show that nuclear localized cyclin D1, an activator of Cdk4/6, is upregulated during kainic acid evoked death of CA3/CA1 neurons and that this upregulation is associated with increased phosphorylation of a critical CDK substrate, pRb. In addition, we find that the CDK inhibitor, flavopiridol blocks the delayed death of cultured cortical neurons evoked by 3-nitroproprionic acid, an inhibitor of the mitochondrial electron transport chain, treatment and that the NMDA antagonist, MK801 provides short term protection in this model. Full, long-term protection occurs when both flavopiridol and MK-801 are present. Taken together, these data support a role for cell cycle regulators in neuronal death evoked by excitotoxic stress and indicate a potential therapeutic target for treatment of excitotoxicity-related disorders.

Animals↗
PubMedDate not supplied

[Influence of voice onset on the perceptual analysis of dysphonia].

The perceptual analysis of voice for 40 dysphonic and normal subjects was studied according to the GRBAS method and with the consensus of three experts. In order to evaluate the effects of voice onset on the evaluation by the jury, we presented two sample materials for each subject: a sustained /alpha/ and the same sustained /alpha/ for which voice onset was suppressed. In a blind test, the two sample materials were presented in the same session in a random way. The jury did not notice the sustained /alpha/ for which voice onset was suppressed.The influence of voice onset on the jury was based on the percentage of identical answers for each material. Our results show that the influence of voice onset is correlated with the dysphonic level. Voice onset would be of major importance for intermediate dysphonia (G1, G2), whereas it seems not to exert any influence in the case of normal voices (G0) or severe dysphonia (G3).

Adult↗
PubMedDate not supplied

Comparison between the GIRBAS Scale and the Acoustic and Aerodynamic Measures Provided by EVA for the Assessment of Dysphonia following Unilateral Vocal Fold Paralysis.

The aim of this study is to establish relevant objective parameters for evaluating dysphonia following unilateral vocal fold paralysis. To do so, the study compares objective and perceptual voice measures. The objective measures were obtained using a voice analysis software (Evaluation Vocale Assistée), whereas the perceptual measures were established with the GIRBAS Scale (grade, instability, roughness, breathiness, asthenia, and strain). All measurements were performed on 40 voice samples: 28 dysphonic subjects with unilateral laryngeal paralysis, and 12 control subjects. The intra- and inter-judge agreements were fairly good, at least for control subjects. The six GIRBAS measures obtained from the pathological voices were higher than those from the control voices (p < 0.001) and the correlation between both groups was good. Grade, breathiness and asthenia correlated with the objective parameters that express the aperiodicity of the phonatory signal (p < 0.01), namely, the coefficient of variability of the fundamental frequency, the coefficient of variability of intensity, and jitter. Our findings suggest that the perceptual reality of laryngeal paralysis-induced dysphonia depends more on grade, breathiness and asthenia than it does on roughness or instability.

Female↗
PubMedDate not supplied

Separate detection of vocal fold vibration by optoreflectometry: a study of biphonation on excised porcine larynges.

This study describes a novel system allowing the noncontact measurement of vibration of each vocal fold. The system is based on reflectometry, i.e. measurement of light bouncing off a vibrating object. The system works in natural light and is sensitive, compact, and inexpensive. We have used this system for separate and simultaneous detection of the vibration of each vocal fold in excised porcine larynges. Normal conditions of vibration and asymmetry of tension leading to biphonations were studied. Analysis of each vibrating cycle reveals interaction between the vocal folds allowing synchronous vibration despite their physical asymmetry or episodes of period doubling.

Animals↗