Sudden deafness in relapsing polychondritis. A scanning electron microscopy study

The left ear of a 57-year-old female who suffered sudden deafness during the course of relapsing polychondritis was examined under a scanning electron microscope. Marked degeneration of the organ of Corti in all turns and dislocated and encapsulated tectorial membrane were found in the cochlea. Marked decrease in number of the sensory cells in the utricular and saccular maculae and total loss of sensory hair bundles in the ampullary cristae of the semicircular canals were seen in the vestibule. These findings strongly suggest that the cause of sudden deafness in this case might be viral. The usefulness of scanning electron microscopy in human temporal bone pathology is stressed.

Angiotensin I-converting enzyme in human urine

It was demonstrated that angiotensin I-converting enzyme was excreted in human urine. The mean activity of the enzyme in normal urine was found to be 0.38 +/- 0.04 (S.E.M.) units/day (n = 18) and the enzymic activity correlated well with the concentration of the excreted sodium (r = 0.76, p less than 0.005). Urinary angiotensin I-converting enzyme was partially purified. Three different molecular weights of enzyme (greater than 400 000, 290 000 and 140 000) were demonstrated by Sephadex G-200 gel filtration. The enzymic properties of these three enzymes were identical with those of angiotensin I-converting enzyme from human lung with regard to inhibitory effects (bradykinin potentiator c and Arg-Pro-Pro), Cl- dependency, pH optimum and KM value.

Purification and some properties of a lethal toxic fragment of staphylococcal alpha-toxin by tryptic digestion

Purified staphylococcal alpha-toxin (molecular weight approximately 36,000) was mildly digested with trypsin, yielding two components by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A fast-moving component (molecular weight 17,000 +/- 5%) which is relatively resistant to tryptic digestion and a slow-moving component (molecular weight 20,000 +/- 5%) which tends to aggregate. The fast-moving component was highly purified by means of combined procedures of column chromatography on Sephadex G-200 with zone electrophoresis on starch. The purified fast-moving component retained a high degree of lethal toxicity for mouse but lacked hemolytic and dermonecrotic activities, whereas the slow-moving component proved to be a nontoxic polypeptide. The lethal toxic fragment was antigenically active showing partial immunological identity with the parent alpha-toxin and stimulated the formation of antibodies capable of neutralizing the lethal action of alpha-toxin in vivo. Some physical properties and the amino acid composition of the purified lethal toxic fragment have been compared with those of native alpha-toxin.

Effects of lectins on the hemolysis of rabbit erythrocytes by straphylococcal alpha toxin

When concanavalin A (1 microgram/ml) or wheat germ agglutinin (2 microgram/ml) was preincubated with a suspension of 2% rabbit erythrocytes for 5 min at 20 C, the binding [125I]-labeled staphylococcal alpha toxin to these erythrocytes was greatly inhibited and the hemolytic action of alpha toxin was decreased. The inhibitory effect of concanavalin A on hemolysis by alpha toxin was completely reversed in the presence of 0.1 M alpha-methyl-D-glucoside or alpha-methyl-D-mannoside. Phytohemagglutinin-P from Phaseolus vulgaris and soybean agglutinin inhibited hemolysis by the toxin at concentrations exceeding 20 microgram/ml. The effect of concanavalin A on alpha-toxin hemolysis was studied further to ascertain the nature of the inhibition. Double reciprocal plots were made of hemolysis against alpha toxin concentrations, and the data suggested that inhibition of the initial rate of the hemolysis by concanavalin A is competitive in nature. This was probably due to an interaction with the alpha toxin binding sites on the cell membrane surface.

Visual suppression of caloric nystagmus in normal individuals

The effects of opening of the eyes and of ocular fixation upon caloric nystagmus were investigated during the period of maximum intensity of caloric nystagmus in a series of 32 normal individuals. The percentage reduction in slow-phase velocity induced depended upon the test conditions, but, on the other hand, did not depend upon the temperature of the water applied as caloric stimulus. This latter fact favors the theory of visual suppression of the caloric test. Another striking finding was that a clear correlation definitely existed between the percentage reduction of suppression in slow-phase velocity and that in the multiplication product of amplitude by nystagmus frequency (P.A.F.) during the period of eye opening and ocular fixation. The percentage of suppression in slow-phase velocity is interchangeable with that in P.A.F., which broadens the practical scope of the routine test.

Studies on habituation of vestibulospinal reflexes. Effects of repetitive optokinetic and vestibular stimuli upon the stepping test

The influence of repetitive applications of optokinetic and vestibular stimuli upon the vestibulospinal responses, measured by the stepping test, was investigated both in an optokinetic training and vestibular habituation test series. Repeated applications of optokinetic and vestibular stimuli modified the rotation angles of the stepping test, i.e. vestibulospinal responses, resulting in a response decline of rotation angles which was still present after 1 month.

Successful replacement of a thrombosed Björk-Shiley mitral valve prosthesis

A case is presented in which 7 months after the first mitral valve replacement (MVR) the malfunction of a Björk-Shiley valve prosthesis was supposed and the thrombosed valve prosthesis was 2 months later successfully replaced. For the detection of the malfunction of the valve prosthesis echocardiography was especially useful.