An ectoprotein kinase of group C streptococci binds hyaluronan and regulates capsule formation.

A 56-kDa protein had been isolated and cloned from protoplast membranes of group C streptococci that had erroneously been identified as hyaluronan synthase. The function of this protein was reexamined. When streptococcal membranes were separated on an SDS-polyacrylamide gel and renatured, a 56-kDa protein was detected that had kinase activity for a casein substrate. When this recombinant protein was expressed in Escherichia coli and incubated in the presence of [32P]ATP, it was responsible for phosphorylation of two proteins with 30 and 56 kDa that were not present in the control lysate. The 56-kDa protein was specifically phosphorylated in an immunoprecipitate of a detergent extract of the recombinant E. coli lysate with antibodies against the 56-kDa protein, indicating that it was autophosphorylated. The E. coli lysate containing the recombinant protein could bind hyaluronan, and hyaluronan binding was abolished by the addition of ATP. Kinetic analysis of hyaluronan synthesis and release from isolated protoplast membranes indicated that phosphorylation by ATP stimulated hyaluronan release and synthesis. Incubation of membranes with antibodies to the 56-kDa protein increased hyaluronan release. The addition of [32P]ATP to intact streptococci led to rapid phosphorylation of two proteins, 56 and 75 kDa each at threonine residues. This phosphorylation was neither observed with [32P]phosphate nor in the presence of trypsin, indicating that the kinase was localized extracellularly. The addition of ATP to growing group C streptococci led to increased hyaluronan synthesis and release. However marked differences were found between group A and group C streptococci. Antibodies against the 56-kDa protein from group C streptococci did not recognize proteins from group A strains, and a homologous DNA sequence could not be detected by polymerase chain reaction or Southern blotting. In addition, Group A streptococci did not retain a large hyaluronan capsule like group C strains. These results indicated that the 56-kDa protein is an ectoprotein kinase specific for group C streptococci that regulates hyaluronan capsule shedding by phosphorylation.

Hyaluronate synthase: cloning and sequencing of the gene from Streptococcus sp.

The complete nucleotide sequence of hyaluronate synthase from Streptococcus sp. and its flanking regions is presented. The gene locus was designated has. Southern-blotting results suggested that the gene was conserved in hyaluronate-producing streptococci. A putative translation-initiation codon was identified and the open reading frame consists of 1566 bp, specifying a protein of 56 kDa. Sequences resembling the promoter and ribosome-binding site of Gram-positive organisms are found upstream of the synthase. The predicted amino-acid sequence reveals the presence of a 35-residue signal peptide. The sequence has some similarity to bacterial peptide-binding proteins.

Recovery of proteins from the broncho-alveolar lavage fluid proposal for a standardisation.

In this study various precipitation methods have been used to concentrate the proteins from broncho-alveolar-lavages. The highest percentage of proteins was recovered from the broncho-alveolar-lavages using the method of Wessel & Flügge (Anal. Biochem. 138 (1984) 141-143). The recovered proteins were further analysed by SDS-polyacrylamide gel electrophoresis. Except for low molecular mass proteins, the method of Wessel & Flügge proved to be the most effective for the recovery of individual proteins. In general, the method of Wessel & Flügge seems to be the superior method for concentrating proteins of broncho-alveolar-lavages for further analysis.

[Non-Hodgkin's lymphoma: a differential diagnosis of otogenic facial paralysis]. / Non-Hodgkin-Lymphome (NHL): Eine Differentialdiagnose der otogenen Fazialislähmung.

Of all the neoplastic conditions of the lymphatic system, Non-Hodgkin's lymphoma (NHL) represents a heterogenous group. As well as lymph nodes NHL can involve extranodal sites, including regions in head and neck. The mouth and oropharynx are typical extranodal sites, and the ENT surgeon should be aware of this possibility of the swift diagnosis of NHL is to be made. We report two patients with rare invasion of the middle ear, facial nerve paresis, and asymptomatic cerebral involvement by Non-Hodgkin's lymphoma.

[Audiologic diagnosis of tumor-induced neural hearing disorders based on discrete finding constellations]. / Audiologische Diagnostik tumorbedingter neuraler Hörstörungen anhand diskreter Befundkonstellationen.

Modern electrophysiological and audiometric tests allow the cause of retrocochlear hearing loss to be diagnosed in almost all cases. Assessment of the stapedius reflex, discrimination using the Fowler test, the ERA findings with respect to inter-peak latency, interaural latency difference of the fifth wave, DORAS (difference between the objective response threshold and the subjective tone threshold), and finally the vestibular findings are all important.

[Familial neural mitochondrial deafness]. / Familiäre neurale mitochondriale Schwerhörigkeit.

Mitochondrial abnormalities are known to cause several neurological syndromes that often include hearing loss as one of their features. We present two brothers with mitochondrial cytopathy and hearing loss. The audiological and electrocochleographic findings suggest a neural origin for the hearing impairment. Muscle biopsy is an important tool for the diagnosis of these syndromes in patients with audiological evidence of a bilateral neural hearing loss and neurological abnormalities.

Shedding of hyaluronate synthase from streptococci.

Hyaluronate synthase was shed into the culture medium from growing streptococci (group C) together with nascent hyaluronate. The mechanism of solubilization was analysed using isolated protoplast membranes. Solubilization increased when membranes were suspended in larger volumes, but it was temperature-independent and was not inhibited by protease inhibitors. Increased hyaluronate chain length enhanced solubilization. The soluble synthase could re-integrate into Streptococcal membranes in a saturable manner. The soluble synthase behaved like an integral membrane protein, although it was not integrated into phospholipid vesicles. In sucrose velocity centrifugation the synthase had a higher sedimentation rate in detergent-free solution, indicating that it existed in an aggregated state.

[Neuro-otologic criteria in the diagnosis of tumor-induced hearing disorders. Studies of 300 patients with acoustic neuroma]. / Neurootologische Kriterien bei der Diagnose "tumorbedingte Hörstörungen". Untersuchungen an 300 Patienten mit Akustikusneurinomen.

Recently, costly technical procedures have been used for the diagnosis of a retrocochlear hearing loss. Electrophysiological methods such as ERA, electrocochleography and promontory tests, and imaging procedures such as CT and MRI have been widely used. Here we demonstrate the diagnostic value of conventional audiometry in retrocochlear lesions. As the clinical audiometric picture shows, a retrocochlear lesion is based on electrophysiological conduction phenomena. The threshold tone decay, absence of stapedius reflex, reduced speech discrimination and ERA findings with electric response decay and synchronization disorders within the brain stem are particularly significant.

[Electrocochleography possibilities in the differential diagnosis of hydrops and neural hearing loss]. / Elektrokochleographische Möglichkeiten zur Differentialdiagnose zwischen hydropischer und neuraler Schwerhörigkeit.

Enhancement of the click-evoked summating potential causing a pathological summation to compound action potential ratio (SP/CAP) in patients with endolymphatic hydrops has been described by several groups. An increased SP/CAP ratio is found also in some patients with a tumour of the cerebellopontine angle. The study of further parameters of the SP/CAP complex, such as the CAP latency and the width of the complex, permit an electrocochleographic differentiation between both forms of hearing loss. The N2 amplitude showed no diagnostic significance.

[Unusual electrocochleography cases]. / Elektrocochleographische Sonderfälle.

The electrocochleographic findings of 3 unusual cases from about 350 performed on patients with various hearing loss are presented; they demonstrate the value of electrocochleography as a clinical tool in otological investigation. The first case was an electrocochleographically detected acute impairment of the first neuron, the second a hereditary hearing loss with endolymphatic hydrops, and the last shows the effect of an endolymphatic shunt on a hydropic hearing loss.

[Acrodysostosis: an autosomal inherited form of peripheral dysostosis]. / Akrodysostose: autosomal vererbte Form der peripheren Dysostose.

We report a 13-year-old boy with peripheral dysostosis, nasal hypoplasia, brachydactyly and a tracheal stenosis of unknown origin. Acrodysostosis is usually caused by an autosomal gene, but in this case it was probably due to a new mutation. The frequently described mental retardation is not essential feature. Ectopic calcification has not been previously reported.

[Frequency-dependent cochlear microphonics in inner ear hearing loss with various pitch thresholds]. / Frequenzabhängige Cochlear Microphonics bei Innenohrschwerhörigkeiten mit unterschiedlichen Tonschwellen.

Promontory recordings of the cochlear microphonics (CM) after stimulation with 0.5, 1 and 2 kHz tone bursts at 120 dB SPL were performed on normal subjects and patients with various, levels of sensory hearing loss. A significant correlation was found between frequency-related CM amplitudes and the configuration of the pure-tone audiogram. Such recordings provide objective information on hearing abilities at low and middle frequencies and are thus a relevant tool in clinical audiometry.

[Increased summation potentials in patients with Menière's disease]. / Vergrösserte Summationspotentiale bei Morbus-Meniere-Patienten.

There have been many publications about enlarged summation potentials with Meniere patients. The phenomenon was interpreted as being due to endolymphatic hydrops. 50 patients were examined electrocochleographically who were suffering from the symptoms low-frequency hearing loss, vertigo, tinnitus and pressure in the ear. As in other previous studies a significantly enlarged negative summating potential was found in 70% of the patients. With 10 patients electrocochleography was performed before and three hours after glycerol ingestion. In 8 patients the SP became smaller, although the subjective hearing threshold improved in only 4 cases. The study shows that enlarged SP is a common finding in Meniere patients; it underlines the diagnostic value of electrocochleography in this disease.

[Retrocochlear hearing disorders]. / Retrokochleäre Hörstörungen.

The diagnosis of retrocochlear hearing impairment is mainly based on threshold tone decay, absence of the stapedius reflex, abnormal dichotic speech discrimination and ERA findings. A relatively poor discrimination for monosyllables with regressive understanding at high intensities can also indicate a neural or central lesion provided that the unaffected side has been correctly masked. ERA results mainly show a synchronisation disorder within the brain-stem, i.e. the J V-response is prolonged or cannot be recorded at all. The cortical response N1, however, corresponds to the subjective threshold except that in impairments of the cortex, the N1-response is worse than expected from the pure tone threshold. Representative examples are given.

Isolation of streptococcal hyaluronate synthase.

Hyaluronate synthase was isolated from protoblast membranes of streptococci by Triton X-114 extraction and cetylpyridinium chloride precipitation. It was identified as a 52,000-Mr protein, which bound to nascent hyaluronate and was affinity-labelled by periodate-oxidized UDP-glucuronic acid and UDP-N-acetylglucosamine. Antibodies directed against the 52,000-Mr protein inhibited hyaluronate synthesis. Mutants defective in hyaluronate synthase activity lacked the 52,000-Mr protein in membrane extracts. Synthase activity was solubilized from membranes by cholate in active form and purified by ion-exchange chromatography.