Diagnostic and management considerations of acquired epileptic aphasia or Landau-Kleffner syndrome

A small number of children have been identified as having an interruption in their communicative progress known as Landau-Kleffner syndrome, acquired epileptic aphasia, or aphasia with convulsive disorder. Although presenting symptoms have differed among the cases reported, a progressive or acute language loss and inattentiveness to auditory stimuli are the most common manifestations. Typically, these children begin developing language normally and then, for no apparent reason, language progress is disrupted. This disruption is accompanied by the onset of seizure activity and/or abnormal electroencephalographic (EEG) findings. While this disorder appears to be relatively uncommon, its frequency is questionable due to its unfamiliarity among the audiology and otology communities and, thus, it is subject to the likelihood of misdiagnosis. A case of acquired epileptic aphasia is described herein. A team diagnostic and management approach, which can include audiology, otology, psychology, neurology, and speech-language pathology is recommended for such cases. Earlier identification of this debilitating disorder is needed in order to secure appropriate intervention and reestablish communication systems for these children.

Long-term results after lateral cranial base surgery

The surgical management of patients with slow-growing benign temporal bone neoplasms has been criticized because of its significant morbidity and mortality compared with results after radiation therapy, but long-term control by irradiation remains unproved. Long-term surgical results have not been studied previously. One hundred twenty-nine skull base operations were performed in 126 patients at the Otology Group, Nashville, Tenn., from January 1970 through May 1987. Fifty-eight patients responded to questionnaires focusing on recovery from loss of cranial nerves. All patients regained some degree of facial function (class V or better), no alimentary tubes or tracheotomies were in use, and no patients had debilitating aspiration. Long-term compensation from the cranial nerve deficits of lateral skull base surgery can be expected in most patients and should not be used as an argument for irradiation in patients with a long life expectancy at time of diagnosis.

Single proline substitutions in predicted alpha-helices of murine granulocyte-macrophage colony-stimulating factor result in a loss in bioactivity and altered glycosylation

Contributions of alpha-helices to biological activity in murine granulocyte-macrophage colony-stimulating factor were analyzed using site-directed mutagenesis and protein expression in COS-1 cells. A series of single proline substitutions were made for residues within the four predicted alpha-helices as a means of disrupting local helical secondary structure. Mutations in three of the four helices resulted in marked reductions in bioactivity. Five mutants E21P, L56P, E60P, L63P, and L107P showed 10(2)-10(4)-fold reduction in bioactivity as well as hyperglycosylation. The same Pro substitutions made on non-N-glycosylated molecules had a similar loss in bioactivity implying that a Pro-induced structural change and not hyperglycosylation was responsible for the major decrease in bioactivity. Additional amino acid substitutions at these residues which conserved charge or hydrophobicity, or replaced the original residue with an Ala, verified that conformational changes in the protein structure were specifically due to steric constraints imposed by the Pro residue rather than loss of important side chain functions.

Functional implication for the topographical relationship between MHC class II and the low-affinity IgE receptor: occupancy of CD23 prevents B lymphocytes from stimulating allogeneic mixed lymphocyte responses

Following the observation of Bonnefoy et al. (J. Exp. Med. 1988. 167:57), that the low-affinity IgE receptor (CD23) on B lymphocytes can be coupled (with the use of chemical cross-linking reagents) to major histocompatibility complex (MHC) class II DR molecules, we now report that ligands binding within the lectin-homology region of CD23 prevent B cells from stimulating allogeneic mixed lymphocyte responses. Ligands capable of blocking mixed lymphocyte responses include the anti-CD23 antibodies MHM6 and EBVCS 4 but not EBVCS 1 and 5. IgE itself, and small peptides representing sequences within the CH3 domain of IgE. The detailed topographical relationship between CD23 and MHC class II on the B lymphocyte surface was examined using dual immuno-fluorescence labeling of cells and direct visualization of the staining by confocal laser scanning microscopy. On transformed B lymphoblasts, the two antigens were seen to co-localize in discrete patches; on normal B cells which had been cultured for 2 days with interleukin 4, CD23 and MHC class II converged at a single pole which exhibited a tendency to pseudopod formation and provided a focus for homotypic cell-cell interactions. The possibility that CD23 could serve as a co-stimulatory-adhesion molecule in antigen presentation by B lymphocytes is discussed with special reference to a potential role in the regulation of IgE synthesis.

Fluorescence quenching; a practical problem in flow cytometry

Dual fluorescence analysis with a single-laser fluorescence-activated cell sorter is dependent on the use of two fluorochromes with similar excitation wavelengths but different emission wavelengths. The dye pair fluorescein and R-phycoerythrin (RPE) have been widely employed for this purpose and interaction between the two dyes has not been observed. Here evidence is presented to show that at high concentrations RPE can completely quench the fluorescein signal in dual fluorescence analysis of human tonsil lymphocytes labelled with pairs of monoclonal antibodies. Reduction in the fluorescein signal correlated with the intensity of red (RPE) staining. This phenomenon can seriously compromise interpretation of dual immunofluorescence carried out on a single laser instrument and can best be avoided by careful analysis of single colour controls.

Alkaline phosphatase-fast red, a new fluorescent label. Application in double labelling for cell cycle analysis

We have observed that the red reaction product of alkaline phosphatase immuno-conjugates and certain substrate preparations produces a brilliant red fluorescence that is visible by fluorescence microscopy using both fluorescein and rhodamine filter combinations. This provides a level of sensitivity greater than that obtained with other commonly used red fluorochromes or by inspection of the reaction product under bright field illumination. Of particular value, the reaction product is unaffected by the denaturing conditions required for the detection of incorporated nuclear BrdU with FITC conjugated anti-BrdU antibody and provides a simple and robust method for the simultaneous detection of cell proliferation and cell surface markers.

The expression of the adenovirus 12 early region 1B 19K protein using a recombinant simian virus 40 system

Using a simian virus 40/adenovirus 12 (Ad12)-recombinant virus, the Ad12 early region 1B (E1B) 19K protein has been produced at high levels after infection of Cos 1 cells. Expression of the 19K polypeptide reaches a maximum at about 48 h post-infection, declining at later times as host cell death occurs. Using two-dimensional isoelectric focusing/SDS-polyacrylamide gel electrophoresis, we have shown that the Ad12 E1B protein is a major species following infection of Cos 1 cells with recombinant virus. Two forms of 19K polypeptide can be distinguished following isoelectric focusing. Using subcellular fractionation of infected cells, it was found that a similar distribution of 19K protein occurred after recombinant virus and Ad12 infection, with the polypeptide being most abundant in nuclear and membranous fractions. Similarly, as in Ad12-infected cells, a certain proportion of the protein is located on the outside surface of the cell after recombinant viral infection. Immunohistochemical studies suggest that, at early times post-infection, the E1B 19K protein is located in the nuclear membrane, the Golgi apparatus and the endoplasmic reticulum. At later times, it can be seen to have spread to the cytoplasm as well as to the other organelles. These results are discussed in relation to the known functions of the 19K E1B protein.

A phenotypic study of B lymphocyte subpopulations in human bone marrow

The regulatory mechanisms that monitor the size of the peripheral B cell pool and determine cell death or survival are poorly understood. In rodents B lymphopoiesis is maintained at a high rate throughout adult life, and under resting conditions there is little recruitment into the long-lived peripheral pool; it therefore follows that most newly formed B lymphocytes have a very short lifespan. The maturation stages of B lymphopoiesis in humans and in experimental mammals appear to be similar. We have determined the phenotype of sIgM- and sIgD-expressing cells from normal adult human bone-marrow and peripheral blood by dual immunofluorescence with an extensive panel of monoclonal antibodies representative of major B cell clusters, in order to identify antigenic differences that may play a regulatory role. Antibodies of the CD21, CD22 and CD9 clusters, the unclustered restricted B antibody 7-F-7 and anti-IgD were reactive with different proportions of sIgM+ cells in blood and bone marrow; 29.5% (range 5-60%) of sIgM+ cells in marrow were sIgD- and most of these cells were also CD21- and CD22-, thus defining a unique marrow population. However, newly formed and mature re-circulating cells comprising the sIgM+sIgD+ population could not be distinguished by the panel of antibodies.

Pathologic findings in the labyrinthine segment of the facial nerve in a case of facial paralysis

The histopathologic findings for a patient with acute facial paralysis caused by herpes zoster oticus who obtained no return of active facial function after 1 year are presented. All imaging studies were nondiagnostic. Biopsy of the labyrinthine segment was performed. Histopathologic analysis showed a sharp line of demarcation between sclerotic nerve proximal to and necrotic nerve distal to the meatal foramen area of the fallopian canal. This finding is consistent with observations that the lesion producing Bell's palsy and herpes zoster oticus usually is situated at the meatal foramen.

Diagnosis and management of paragangliomas of the skull base

In appropriately selected patients, glomus tumors of the head and neck are best treated surgically. Unresectability is not a factor in therapeutic planning for local disease control. Existing techniques and exposures for tumor removal can be reliably applied to these paragangliomas, with acceptable morbidity and mortality. A team approach to this problem is mandatory.

Surgical management of cholesteatoma in an only hearing ear

The patient with a cholesteatoma in an only hearing ear presents a management dilemma: how best to treat the patient to minimize the chances of developing a severe hearing loss in that ear. Twelve patients managed surgically for cholesteatoma in their only hearing ear are reviewed. The location and extent of the cholesteatoma, the type of operation performed, and postoperative hearing results are presented. Eleven of the 12 patients maintained their bone-conducted speech reception threshold to within 5 dB of the preoperative level during follow-up periods of 2 months to 4 years. Recommendations are made regarding preoperative evaluation, perioperative use of antibiotics and steroids, operative planning, ossicular reconstruction, and postoperative care. Special attention is given to the evaluation and management of the ear that has a fistula eroding into the cochlea and semicircular canals, both when suspected from preoperative imaging studies and when discovered intraoperatively.

Studies on the subsite specificity of the rat brain puromycin-sensitive aminopeptidase

The specificity of the puromycin-sensitive aminopeptidase from rat brain was examined. Using L-alanyl-beta-naphthylamide as substrate Vmax of the reaction was shown to be pH independent over the range of 5.5-9.0, while Km exhibited a pKa of 7.7. This latter value corresponds to the pKa of the amino group of the substrate. Using X-Ala and X-Leu to examine the specificity of the P1 site it was found that Arg and Lys exhibit the highest affinity, followed by Met, Val, Leu, Trp, and Phe, which bind congruent to 5- to 20-fold less well. Although Km varied more than 20-fold within this series, Vmax showed considerably less variation. Significantly weaker binding was observed with a P1 Gly, Ala, Ser, or Pro with no binding detectable with a P1 Glu. The presence of a P'1 Leu compared to P'1 Ala results in an approximate 10-fold decrease in Km with little change in Vmax. The effect of varying P'1 residues was examined with the series Leu-X. In this case basic and hydrophobic amino acids, with the exception of Val, all exhibit nearly the same Km. The binding of Arg-Arg and Lys-Lys showed the same Km as obtained for Arg-Leu or Lys-Leu, respectively. When Leu-Ser-Phe was compared to Leu-Ser the P'2 residue led to a 100-fold decrease in Km and slightly less than a 5-fold increase in Vmax. In contrast the addition of a P'2 Met to Leu-Trp results in only a 3-fold decrease in Km and a 3-fold increase in Vmax. The results indicate a preference for a basic or hydrophobic residue in the P1 and P'1 sites and indicate subsite-subsite interactions which primarily affect binding.

Management of large dural defects in skull base surgery: an update

The use of a ventriculoatrial shunt for long-term CSF diversion for reconstruction after resection of large skull base tumors with intradural extension has been discontinued. The concern about placing a permanent foreign body in a wound open for 12 to 18 hours is our primary reason for changing the technique. Our present approach uses a rectus abdominis microvascular free flap over the fascial closure of the dural defect. Although our experience with this technique is limited, the advantages over the technique used previously warrant its continued use.

Auditory dysfunction caused by multiple sclerosis: detection with MR imaging

We reviewed the MR examinations of 167 patients who presented over a 3-year period with a chief symptom of hearing loss and/or tinnitus. In 14 of these patients the only MR abnormality was the presence of multiple parenchymal high-signal foci on T2-weighted images. Nine of the 14 had clinical evidence of multiple sclerosis; the remaining five had no clinical evidence of multiple sclerosis. Lesions in the auditory pathways, potentially responsible for the patients' symptoms, were identified in only five cases. We recommend T2-weighted images of the whole brain in addition to T1-weighted images of the internal auditory canals and cerebellopontine angles in patients with hearing loss. In some patients, lesions found at higher levels in the periventricular white matter may provide the only clue to the origin of auditory abnormalities.

Deletion of carboxy-terminal residues of murine granulocyte-macrophage colony-stimulating factor results in a loss of biologic activity and altered glycosylation

A deletion mutant of murine granulocyte-macrophage colony-stimulating factor (GM-CSF) which differs in primary structure from native GM-CSF in the carboxy-terminal 11 amino acids was prepared. Four amino acid residues are mutated and the seven terminal residues including Cys-118 are deleted. Supernatants from COS-1 cells transfected with this deletion mutant (GM-CSF(del] showed a 3000-fold decrease in the ability to stimulate bone marrow stem cells to proliferate and differentiate into granulocytes and macrophages in vitro. Northern blot analysis using poly(A)+ RNA extracted from the transfected cells showed equal accumulations of GM-CSF and GM-CSF(del). Transfection with full-length GM-CSF followed by immunoprecipitation of metabolically labeled supernatant proteins with rabbit anti-rGM-CSF antiserum yielded predominantly the 23-kDa, fully glycosylated form and small amounts of both a 29-kDa form and the 18-kDa non-N-glycosylated form. Transfection of the GM-CSF(del) mutant and immunoprecipitation revealed a large, diffuse band on sodium dodecyl sulfate--polyacrylamide gel electrophoresis with a molecular weight of about 29 kDa. Digestion of the immunoprecipitated 29-kDa species with N-glycanase converted the 29-kDa form into two forms of about 23 and 18 kDa, suggesting that the increase in molecular weight of the deletion mutant protein resulted from hyperglycosylation. Adding tunicamycin to the culture medium of cells transfected with GM-CSF(del) also yielded a single non-N-glycosylated species of about 18 kDa, but secretion was at a significantly lower level than either the 29-kDa hyperglycosylated GM-CSF(del) protein from non-tunicamycin-treated cells or the 18-kDa non-N-glycosylated full-length GM-CSF from tunicamycin-treated cells. Since very recent scanning-deletion analysis indicates that there is a critical region for activity near Cys-118 and that Cys-118 is necessary for maximal activity, we conclude that the Cys-118 residue is necessary for proper glycosylation and maximal biologic activity of GM-CSF.

Transient production and secretion of human transforming growth factor TGF-beta 2

Transient transfection of simian COS cells with a recombinant plasmid encoding the human transforming growth factor TGF-beta 2 precursor protein results in the production of a latent, biologically inactive protein. Upon acidification, recombinant TGF-beta 2 exhibits full biological activity, including inhibition of mink lung epithelial cell growth, stimulation of anchorage-independent growth of murine embryonic fibroblasts, and competition for TGF-beta receptor binding. Further analysis of conditioned media with antiserum to either a pro- [amino acid (aa) residues 1-220] or mature [aa 297-414] peptide of the TGF-beta 2 precursor suggests that TGF-beta 2, similar to TGF-beta 1 production in Chinese hamster ovary cells [Gentry et al., Mol. Cell. Biol. 7 (1987) 3418-3427], is initially synthesized as a larger precursor protein which is proteolytically cleaved to yield the mature 112-aa transforming growth factor.

Facial nerve paralysis with benign parotid masses

Facial paralysis in the presence of a parotid mass has been associated classically with a presumed diagnosis of malignancy. However, isolated case reports have documented the occurrence of paresis or paralysis secondary to pathologically benign, nonneurogenic parotid lesions. These previous cases have been reviewed and three additional cases are described. Comparisons are made on age, sex, symptoms, physical findings, pathologic findings, and prognosis. Involvement of the seventh nerve may be explained on the basis of compression, especially in association with local inflammation. Although facial paralysis still should be considered indicative of a malignancy, it also may be caused by benign masses, particularly those associated with rapid enlargement and/or infection.

A human tRNA gene heterocluster encoding threonine, proline and valine tRNAs

A cluster of three tRNA genes encoding a tRNA(UGUThr), a tRNA(UGGPro), and a tRNA(AACVal), and two Alu-elements occur in a 6.0-kb human DNA fragment. The tRNA(Thr) gene is 2.7-kb upstream from the tRNA(Pro) gene, which is separated by 367 bp from the tRNA(Val) gene. One Alu-element actually overlaps the tRNA(Val) gene and is of opposite polarity to all three tRNA genes. All three tRNA genes are accurately transcribed in a homologous HeLa cell extract, since the ribonuclease T1 fingerprints of the tRNA transcripts are consistent with the nucleotide sequences of the tRNAs. The upstream region flanking the tRNA(Thr) gene has two tracts of alternating purine/pyrimidine residues potentially capable of adopting the Z-DNA conformation, and presumptive binding sites for two RNA polymerase II transcription factors. The tRNA(Thr) gene apparently has a substantially higher in vitro transcriptional efficiency than the other two tRNA genes in this cluster, and a tRNA(GCCGly) gene from another human DNA segment. Deletion constructs of the tRNA(Thr) gene retaining 272, 168, and 33 bp of original 5'-flanking DNA had about the same in vitro transcriptional efficiency, whereas that of the construct with only 2 bp of 5'-flanking human DNA was drastically reduced. The tRNA(Thr) gene constructs with 272 and 168 bp of original 5'-flanking DNA apparently reduce the transcriptional efficiencies of the proline and glycine tRNA genes, implicating the upstream region from the tRNA(Thr) gene as being crucial for its high transcriptional efficiency.

A paraneoplastic syndrome associated with glomus tumors of the skull base? Early observations

Independent secretion of vasoactive substances by glomus tumors of the skull base is widely recognized. Surgical removal of these tumors often results in an unexplained prolonged postoperative ileus, even in cases in which the vagus nerve is preserved. There is evidence that these tumors may secrete neuropeptides, such as cholecystokinin, in addition to catecholamines. A retrospective analysis of cases of glomus tumors of the skull base operated on at The Otology Group was carried out to correlate preoperative neuropeptide levels, vagus nerve status at surgery, and duration of postoperative ileus. High circulating levels of cholecystokinin associated with these tumors may be responsible for the unexplained phenomenon of prolonged postoperative ileus. The relevance of neuropeptides to the postoperative management of these patients is discussed. Preventive measures that may avert the potentially lethal complications of aspiration and negative nitrogen balance are described.

CD23: a multi-functional receptor/lymphokine?

With the demonstration of identity between CD23 and the low affinity IgE Fc receptor (Fc epsilon RII), two previously separate avenues of immunological research have converged into one. Particularly in its guise as 'Blast-2' antigen, evidence has been mounting to implicate CD23 as an important molecule in B-cell growth regulation. It might seem pertinent, however, to question a role for an apparently isotype-specific immunoglobulin (Ig) receptor in general B-cell processes. In this article, John Gordon and colleagues attempt to reconcile the two, currently diverse, schools of thought regarding the primary function of CD23 and to provide a structural model that accounts for the biological pleiotropy observed.

What I think of sac surgery in 1989

The senior author has performed shunt procedures routinely for medically refractory cases of Meniere's disease starting in 1964 and ending in 1984. Five hundred and sixty-eight consecutive patients were operated on and followed from 1970 to 1984. Combining the cases of C. G. Jackson, there have been a total of 676 procedures done at the Otology Group. Initially endolymphatic-subarachnoid (ES) shunts were used, then endolymphatic-mastoid shunts (EM), and most recently, the Denver valve has been employed. No significant difference between these procedures was noted in the control of vertigo or stabilization of hearing. Successful resolution of vertigo occurred in less than 60%. Sac surgery at the Otology Group, therefore, has been abandoned in favor of vestibular nerve section for the surgical management of medically refractory Meniere's disease with disabling vertigo.

The auditory brain stem response interaural latency difference (ILD) in patients with brain stem lesions

The ABR interaural latency difference (ILD) from 15 patients with brain stem lesions was compared to the ILDs from patients with VIIIth nerve tumors, cochlear pathology, and a normal control group. All patients in the study had to meet the criteria of bilaterally symmetrical hearing for pure-tone thresholds in order to offset the effect of hearing loss on the ILD. Although the ILDs for the brain stem lesion group were larger than for the cochlear or normal groups, they were significantly smaller than for the VIIIth nerve tumor group. It appears that the ILD is not as sensitive a measure for detecting brain stem involvement as VIIIth nerve tumors.