Electrical alternans of pacemaker spike amplitude: an unusual manifestation of permanent pacemaker generator malfunction

A case of electrical alternans of pacemaker stimulus amplitude is presented, with constant alternation of large and small amplitude pacemaker spikes without loss of ventricular capture, due to a defect in the oscillator hybrid of a rate programmable Medtronic unit. This represents an unusual electrocardiographic manifestation of pacemaker generator malfunction which, to our knowledge, has not been reported previously.

Sac decompression for refractory luetic vertigo

Luetic hydrops can occur in both congenital and acquired lues and otologic manifestations may be indistinguishable from Meniere's disease. Eight endolymphatic sac decompression procedures were performed on 6 patients with refractory luetic vertigo. Of those, 3 had congenital and 3 acquired lues. All cases had received extensive anti-luetic medical therapy without any discernible improvement in the vertiginous attacks. In our 6 patients with luetic hydrops the main complaint was severe refractory vertigo, indeed, disabling in most cases. Postoperatively, all cases remained free from these severe attacks and the vertigo was controlled or eliminated in all cases. Although hearing was improved in one patient, hearing seemed not to improve, generally speaking, as a result of the long-term postoperative follow-up. We describe our method of sac decompression and drainage and suggest that this procedure might be considered for patients with uncontrollable luetic vertigo who have not benefited from adequate medical therapy.

Enzymatic trimethylation of residue-72 lysine in cytochrome c. Effect on the total structure

A highly purified protein methylase III from Neurospora crassa or Saccharomyces cerevisiae specifically methylates a single lysine residue of position 72 of horse heart cytochrome c. The enzymatically methylated cytochrome c has been separated from the unmethylated counterpart species by isoelectric focusing. Simultaneously, the pI values of these two species were found to be 9.49 and 10.03, respectively. Since methyl substitution increases the basicity associated with the epsilon-amino group of lysine residues, the observed decrease in pI value is in opposition to the predicted increase. Space-filling models revealed the possibility of a hydrogen bond between the oxygen of amide of residue-70 asparagine and the epsilon-amino nitrogen of residue-72 lysine in unmethylated horse heart cytochrome C. the enzymatic methylation of residue-72 lysine tends to dissociate this hydrogen bond, thereby possibly inducing the shift of 'effective charge' of the protein molecule. This paper also deals with the pI values of cytochromes c from 13 different sources, determined by the isoelectric focusing technique.

Effects of a brief low-level exposure to the particulate fraction of diesel exhaust on pulmonary function of conscious sheep

This study was undertaken to determine the effects of an acute low-level exposure to diesel exhaust particulate material on pulmonary function in conscious sheep. This was accomplished by measuring pulmonary mechanics, airway reactivity to increasing doses of aerosolized carbachol, and tracheal mucous velocity both prior to and immediately after exposure to the diesel exhaust particulates. The diesel exhaust particulate material was aerosolized by a fluidized-bed dust generator. The mass concentration of the dust ranged between 400 to 500 micrograms/m3 and a mass median aerodynamic diameter of 2.8 micrometers. The sheep breathed the diesel exhaust particulates for 30 min by means of a Plexiglas helmet. The particulates caused no material alteration in pulmonary resistance, airway reactivity to aerosolized carbachol, or static lung compliance when compared to pre-exposure values. Tracheal mucous velocity was likewise unaffected. In conscious sheep under the present exposure conditions, the diesel exhaust material administered as a respirable aerosol does not materially affect the function of the large airways, the elastic properties of the lung, nor tracheal mucous transport.

Pathology of chronic otitis media

A review of 800 pathological temporal bones collected from autopsy cases revealed 333 ((41.6%) to have some type of otitis media; purulent otitis media (52.5%), serous otitis media (6%), mucoid otitis media (4.5%), and chronic otitis media (36.9%). The 123 temporal bones with chronic otitis media were further studied and found to have granulation tissue, cholesteatoma, cholesterin granuloma, bone changes, and fibrosis. Other findings included tympanic membrane perforation, tympanosclerosis, metaplasia of the epithelium with subepithelial glandular formation, suppuration, labyrinthitis, and evidence of complications of chronic otitis media (meningitis, subdural abscess, brain abscess, petrositis, and endolymphatic hydrops). From this study it was concluded: 1) chronic otitis media occurred quite frequently, from a histological standpoint, in the absence of tympanic membrane perforation; 2) granulation tissue in temporal bones was found much more frequently in chronic otitis media than was cholesteatoma; and 3) complications and sequelae of otitis media tended to occur more commonly secondary to granulation tissue than to cholesteatoma.

ABO-incompatible bone marrow transplantation: preparation by plasma exchange and in vivo antibody absorption

The threat of fatal hemolytic transfusion reaction has been a major deterrent to the use of ABO-incompatible bone marrow donors. An eighteen year old type O male with acute leukemia was prepared to receive type A HLA identical marrow using large volume plasma exchange prior to and following cyclophosphamide administration. Saline agglutinating anti-A antibody was initially present at a titer of 1:128. The initial antiglobulin titer of dithiothreitol (DTT) treated serum was 1:64. Initially the T 1/2 of 51Cr labeled type A red blood cells was less than five minutes. The first plasma exchange removed large quantities of anti-A antibody but 51Cr survival of type A red blood cells was unchanged. A second plasma exchange after an interval of three days, increased the T 1/2 of 51Cr labeled cells to 20 minutes. Saline agglutinating anti-A was not present at a titer of 1:8 and the antiglobulin titer of DTT treated serum was 1:4. Reaction to subsequent transfusion of type A red blood cells (5 units) was limited to a single febrile episode during the first unit. Survival of 51Cr labeled red blood cells increased to T 1/2 equal to 21 hours. These data indicate that plasma exchange and infusion of ABO incompatible red blood cells effectively reduce antibody concentration and prolong survival of ABO incompatible erythrocytes. It is suggested that the prolongation of 51Cr survival of ABO-incompatible red blood cells to a point that extravascular destruction is predominant be used to establish the safety of ABO-incompatible marrow infusion.

Mastoidectomy update

The long-term results of 375 primary mastoidectomy operations for chronic otitis media and chronic mastoiditis are described and discussed. Two-thirds of these cases were open cavity mastoidectomies and 1/3 closed cavity mastoidectomies. Primary pathology was cholesteatoma in 1/3 and granulation tissue in 2/3 of the cases. The method of reducing the size of the mastoid cavity by sculpturing mastoid cavity by sculpturing mastoid cortical bone is most important in avoiding large postoperative cavity problems. Principles and methods are described. Healing (dry ear) is a more important management objective than hearing and, indeed, enhances the prospects of obtaining a long-term hearing result. Three important phases of controlling mastoid disease (preoperative, operative, and postoperative) are equally stressed. Intact wall tympanomastoidectomy is not recommended in sclerotic mastoids (the majority of our cases) as being unsafe and unnecessary. Revisions, mostly minor, were done in 31% of the cases for a total of 521 procedures. We recomment a one-stage tympanomastoidectomy. Multiple planned procedures are, in the main, unnecessary and should be avoided to reduce unnecessary hospitalization and expense.

Pathogenesis of otitis media

Pathogenesis of otitis media was studied in humans and various animal models primarily from a pathological and chemical point of view. Findings were correlated and interpreted for various forms of otitis media in longitudinal and parallel studies, including acute purulent otitis media (POM), serous otitis media (SOM), mucoid or secretory otitis media (MOM), and chronic suppurative otitis media (COM), especially as regards the continuum or interrelated changes of various groups. Purulent otitis media was produced in chinchillas by direct inoculation of less than 100 pneumococci into the middle ear space. Serous otitis media was produced in chinchillas and cats following Eustachian tube obstruction with silicone. Mucoid otitis media followed the development of SOM in cats after two to four weeks of tubal occlusion. Samples of middle ear effusion (MEE) and serum, obtained from children with SOM and MOM after myringotomy for ventilation tube placement, were evaluated. The three components studied were MEE, epithelium and the subepithelial space (SES). Inflammatory changes in the SES were significant for all forms of otitis media, but especially for POM and SOM. Epithelial metaplasia to secretory cells was most prominent in MOM. Chemical factors involved in pathogenesis and defense were studied. Lactic dehydrogenase and lysozyme, chemical indicators of inflammatory activity, were greater in POM and MOM than in SOM. Immunoglobulins (A, G, & M) were greater in MOM than in SOM. The similarity of findings between the groups suggests a strong relationship between them. The ability of certain types of otitis media to evolve into another substantiates the concept of the continuum for some patients. Pathogenesis is dependent upon various extrinsic factors of etiopathogenesis, while the form that otitis media takes seems to rely mostly on relative activity of the SES and the epithelium.

Light and electron microscopic studies of megakaryocytes in Korean epidemic hemorrhagic fever

A retrospective study was devised to determine the correlation between myelography and computed tomography (CT) in the recognition of abnormalities of the lumbar intervertebral disk. A group of 106 patients was studied who had had both myelography and CT within a 6 week period. Each examination was interpreted separately by a neuroradiologist who had no access to the patients' clinical findings or the results of any radiologic studies. On comparison of 290 interspace levels, there was agreement in definite abnormalities in 70%. Most discrepancies were due to suspicious findings and inconclusive studies of both kinds. In particular, there was poor correlation between the two examinations in the diagnosis of a slightly bulging disk. The major discrepancy rate was less than 5% overall and less than 1% among patients without prior surgery. On the basis of these findings, a diagnostic algorithm is suggested that would facilitate the workup of a similar group of patients.

Microcirculation of the lymph node with metastases

Microangiographic and histologic examination of the popliteal lymph node was performed on 49 rabbits 3 to 55 days after V2 tumor implantation into the hind paw. Control animals received subcutaneous tissue extract from normal rabbit donors. During the first 10 days after the tumor implant from an allogeneic animal donor, the draining lymph node exhibited a hypervascular response which after 2 weeks gradually subsided. Subsequently, during the early stages of lymph node metastasis there was still hypervascularity adjacent to the metastatic deposit. In about 4 weeks the metastases became more established and surrounded by layers of plasma cells. The hypervascular changes of the surrounding lymph node subsided by this time. In lymph node metastases the microvasculature could be an indicator of the immunologic activity of the host.