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Biomedical subjects

S Bobin

Publications and source records attributed to S Bobin.

At least 19 recordsLinked to original sources

Structure of Saccharomyces cerevisiae alpha-agglutinin. Evidence for a yeast cell wall protein with multiple immunoglobulin-like domains with atypical disulfides.

alpha-Agglutinin of Saccharomyces cerevisiae is a cell wall-associated protein that mediates cell interaction in mating. Although the mature protein includes about 610 residues, the NH2-terminal half of the protein is sufficient for binding to its ligand a-agglutinin. alpha-Agglutinin20-351, a fully active fragment of the protein, has been purified and analyzed. Circular dichroism spectroscopy, together with sequence alignments, suggest that alpha-agglutinin20-351 consists of three immunoglobulin variable-like domains: domain I, residues 20-104; domain II, residues 105-199; and domain III, residues 200-326. Peptide sequencing data established the arrangement of the disulfide bonds in alpha-agglutinin20-351. Cys97 is disulfide-bonded to Cys114, forming an interdomain bond between domains I and II. Cys202 is bonded to Cys300, in an atypical intradomain disulfide bond between the A and F strands of domain III. Cys227 and Cys256 have free sulfhydryls. Sequencing also showed that at least two of three potential N-glycosylation sites with sequence Asn-Xaa-Thr are glycosylated. At least one of three Asn-Xaa-Ser sequences is not glycosylated. No residues NH2-terminal to Ser282 were O-glycosylated, whereas Ser282, and all hydroxy amino acid residues COOH-terminal to this position were modified. Therefore O-glycosylated Ser and Thr residues cluster in the COOH-terminal region of domain III, and the O-glycosylation continues into a Ser/Thr-rich sequence that extends from domain III to the COOH-terminal of the full-length protein.

Agglutinins

Twice daily cefpodoxime proxetil compared with thrice daily amoxicillin/clavulanic acid for treatment of acute otitis media in children.

A total of 260 children, 3 months to 11 years old (median age 24 months), with acute otitis media (AOM) received either cefpodoxime proxetil (CP) 8 mg/kg/d b.i.d. or amoxicillin/clavulanic acid (ACA) 40/10 mg/kg/d t.i.d. for 8 days. A significant difference in clinical cure rates was observed between the CP group 71/118 (60%) and the ACA group 42/105 (40%), p = 0.003. At the follow-up visit (20-30 days after the start of treatment), significant advantages were recorded with the CP vs. ACA therapy, in terms of satisfactory clinical response [90/111 (81%) vs 60/94 (63.8%), p = 0.005] residual middle ear effusion (14.4% vs 28.7%, p = 0.01) and normal tympanometry (78% vs 61.4%, p = 0.017). Compliance and adverse event frequency were the same in both treatment groups. The higher clinical cure rate and equivalent safety profile of CP indicates that it is an acceptable alternative to ACA for the treatment of AOM in children.

Acute Disease

[Spectral study of laryngotracheal sounds. Methodological approach and perspectives].

Prior studies have shown that laryngotracheal sounds are vectors of objective information which indicate the origins and mechanisms of sound production. The first objective of this study is to confirm these earlier findings on a larger scale. The second objective is to develop a simple apparatus which permits the rapid acquisition and analysis of information for a prompt diagnosis. This study will be carried out in infants referred to the Department of otolaryngology of the Kremblin-Bicêtre Hospital over the next two years. The material and methods used are described.

Humans

[Cholesteatoma of the middle ear with closed tympanic membrane in children. Apropos of 8 cases].

Among 30 children with cholesteatoma undergoing surgery at the Bicetre Hospital between 1985 and 1990, 8 had intact tympanic membranes. Since this represents a larger portion of the patient population than would be expected from previously published data, we under-look a critical analysis of the clinical findings. Among these 8 cases, 2 corresponded to the criteria of congenital cholesteatoma with no history of otitis or trauma and 3 corresponded to acquired types with histories of ventilatory intubation, myringoplasty and accidental trauma. Finally, 3 cases were possibly of mixed origin with lesions typical of congenital epithelial rests and a history of commonplace era infections. Based on these observations, the authors review the clinical characteristics and pathogenesis of congenital cholesteatoma and evoke the etiologic impact of trauma, particularly iatrogenic events such as myringoplasty and ventilatory intubation.

Child

[Cholesteatoma and petro-mastoid excision. Indications and results apropos of 36 cases].

An open operative technique was used in 36 (38%) of 95 patients with chronic cholesteatomatous otitis followed up by the same surgeon between 1986 and 1990. Although a good anatomical result was obtained in 88% of cases the functional result was less evident, since 57% of patients were left with a liminal tonal loss of less than 30 décibels. The reasons for using an open technique are analyzed, but in only 5% of cases could the possibility of using a closed technique be envisaged, making the classical discussion between open and closed methods of treatments of only academic interest. Petromastoidian evidement with reorganization of the cavity is considered to be effective therapy for cholesteatoma, but indications and technical procedures must be adhered to strictly.

Adolescent

[Syndrome of obstructive sleep apnea in children].

Sleep apnea syndrome (SAS) in children has been identified only recently. Its incidence is unknown but seems to be rising. The cause is usually an obstruction (enlarged tonsils) that alters the fragile physiologic mechanisms responsible for maintaining the upper airways open when the child is sleeping. Diagnosis of SAS rests on clinical findings. The parents should be questioned as to the frequency over time of the various symptoms, of which most occur during the night: snoring, difficult breathing, respiratory pauses. Sleep polygraphy studies are indicated only in specific situations. The main cause is enlargement of the adenoids and tonsils. Cardiovascular complications may develop; weight gain and statural growth, psychomotor development and development of the face may be altered. Chronic snoring without apneas should be considered as a form of SAS. Treatment rests mainly on surgery (removal of the adenoids and tonsils).

Blood Gas Analysis

Characterization of the CRPCY core formed after treatment with carboxypeptidase Y.

CRP is resistant to attack by carboxypeptidase Y at 37 degrees C, whereas cAMP-CRP is digested yielding a core terminating at Thr-202 and lacking the seven carboxyl-terminal amino acid residues. A similar core (CRPCY) is formed when CRP is incubated with carboxypeptidase Y at 47 degrees C in the absence of cAMP. CRPCY has a more open conformation than CRP at 37 degrees C. While unliganded CRP is resistant to trypsin, CRPCY is sensitive to tryptic attack. Dithionitrobenzoic acid-mediated intersubunit disulfide crosslinking of CRP requires cAMP, CRPCY subunits are crosslinked in the absence of cAMP. The carboxyl-terminal region of unliganded CRP is conformationally restricted at 37 degrees C. The CRPCY retains cAMP binding activity. The CRPCY which terminates at Thr-202, no longer binds lac P+ DNA nor stimulates abortive initiation by RNA polymerase from the lac P+ promoter. The results indicate that the C-terminal region of CRP participates in the conformational stability of the closed form of CRP and indirectly in DNA binding by the open cAMP-CRP conformer.

Carboxypeptidases

[Objective tinnitus and palatal myoclonus. A new therapeutic approach].

The syndrome combining velar myoclonia with objective tinnitus is rare and, in adults, it corresponds most of the times to a neurological lesion of the dento-olivary tractus. Its functional manifestations are often invalidating and propounded medical treatments uneffective. The authors report a case in which local injection of botulinus toxin allowed to obtain satisfactory functional improvement. Such therapy may prove useful when conventional management is failing.

Adult

[Obstructive sleep apnea-hypopnea syndromes in children. Therapeutic results].

43 children with a clinical suspicion of obstructive sleep apnea-hypopnea were studied. All children underwent clinical examination and a standardised questionnaire was completed by their parents in order to investigate the principal nocturnal and diurnal symptoms present. A sleep study was performed. In addition to methods designed to identify the stage of sleep (EEG, EOG, EMG), this included recording of nasal and buccal airflow, thoracic and abdominal respiratory movements and blood gas analysis. 38 children has recordings during their afternoon nap, and 4 children during the night. Tonsillar hypertrophy was the principal etiology responsible for nocturnal respiratory disorders (33 cases). In addition, other etiologies were demonstrated: Pierre Robin syndrome, cranio-facial stenosis, laryngomalacia, Prader-Willi syndrome and Arnold Chiari malformation. Surgery was performed in 31 children: 22 tonsillectomies with or without adenoidectomy, 4 uvulo-palato-pharyngoplasties with tonsillectomy, 3 epiglottoplasties and 2 staphylorrhaphies. Long-term results were studied clinically and in 11 cases by polysomnographic recording.

Airway Obstruction

[Cholesteatoma of the ear].

Cholesteatoma of the ear is characterized by the presence of a keratinizing squamous epithelium in the cavities of the middle ear. The epithelium invades the ear either by direct migration or by retraction of the eardrum. Owing to is potentials for migration, desquamation, bone erosion and infection, it is for most of the complications of chronic otitis and fully justifies the adjective "dangerous" applied to chronic cholesteatomatous otitis. The clinical diagnosis rests on microscope otoscopy. Audiometry informs on the degree of hearing loss and on the state of the contralateral ear. Standard radiography and computerized tomography of the petrous bone evaluate the extent of the lesion. Treatment is purely surgical: it consists of excision of the entire epithelium that has entered the middle ear and, secondarily, conservation or improvement of hearing. Whatever the surgical technique used, the frequency of recurrences calls for long-term follow-up.

Cholesteatoma

Magnetic resonance investigations of non-acoustic petrous lesions.

Twenty cases of intrapetrous lesions were studied by a 1.5 T magnetic resonance (MR) unit. In all cases, comparisons were made between MR, CT and clinical findings. Our present material included 9 cholesteatomas, 1 cholesterol cyst, 3 primary epidermoid carcinomas, 2 metastatic neoplasms, 1 glomus jugulare tumor and 4 facial neurinomas. Gadolinium was injected in 7 cases and seemed to be the best method for studying the intrapetrous tumors. MR permitted accurate topographic study and assessment of tumoral extension, as well as a ready demonstration of tumor vascularity. The present findings also showed that MR is not capable of defining small bony detail or calcifications.

Adolescent