Auditory deprivation of the central auditory system resulting from selective inner hair cell loss: animal model of auditory neuropathy

Auditory neuropathy is often characterized by normal thresholds, present otoacoustic emissions, poor speech discrimination, absent acoustic reflexes, absent or abnormal auditory brainstem response waveform, but normal late cortical potential. This paper describes an animal model that has many characteristics of auditory neuropathy. Chinchillas can be deprived of a significant portion of the neural inputs to the central auditory system by administering carboplatin, an antineoplastic agent that selectively destroys inner hair cells (IHCs) and type I auditory nerve fibers. Selective IHC loss has no effect on distortion product otoacoustic emissions or the cochlear microphonic potential, implying normal outer hair cell function. However, selective IHC loss causes the amplitude of the compound action potential to decrease in proportion to the degree of IHC loss. However, the threshold of the CAP shows little increase with mild to moderate IHC loss. Acoustically responsive auditory nerve fibers in ears with mild to moderate IHC loss have normal thresholds and tuning curves with narrowly tuned tips. Although the central auditory pathway is deprived of much of its sensory inputs, the amplitude of the local field potential in the auditory cortex was normal or enhanced, while those from the inferior colliculus were slightly reduced. The results are related to those of a patient with auditory neuropathy.

Reduction of benzodiazepine receptor binding is related to the seizure onset zone in extratemporal focal cortical dysplasia

PURPOSE

Comparison of regional reduction of GABA receptor binding and seizure onset zone in patients with extratemporal epilepsy due to focal cortical dysplasia.

METHODS

Two patients with frontal lobe epilepsy who remained seizure free after partial frontal lobe resection were investigated with magnetic resonance imaging, positron emission tomography (PET) with 18F-fluoro-deoxy-glucose (FDG) and 11C-flumazenil, subdural EEG-video recordings, and postoperative benzodiazepine (BDZ)-receptor autoradiography.

RESULTS

The area of reduced BDZ-receptor binding as documented by preoperative flumazenil-PET and postoperative BDZ-receptor autoradiography corresponded to the seizure onset zone and was smaller than the interictal hypometabolism documented by FDG-PET.

CONCLUSION

Flumazenil-PET is a useful tool for localization of the epileptogenic zone in patients with extratemporal epilepsy caused by focal cortical dysplasia. Neuronal distribution of BDZ-receptor density confirms in vivo flumazenil-PET findings. The regional reduction of BDZ-receptor binding in focal cortical dysplasia seems to be confined to the seizure onset zone and not to the extent of dysplastic cortex.

[Prevention of pregnancy in bitches with the progesterone antagonist anglepristone (alizone)]

A study was carried out between April 1997 and October 1998 to determine the effect of the progesterone antagonist, Aglépristone (Alizine), for the prevention of pregnancy. 93 bitches were treated, because of mismating, with Aglépristone. The owners were then contacted 2 weeks and 6 to 12 months after treatment to gather any information on effects noted over this period. The major questions were, was pregnancy prevented and if so what side effects were observed, if any, and whether any metropathies were diagnosed. Also noted was the beginning of the next heat and, if the bitch was mated, the fertility rate. Pregnancy was seen in only one bitch. In 51 bitches minor side effects, either singularly or in combination, such as a transient itch, vaginal discharge, reduced appetite, tiredness or attachment were observed. The fertility was not influenced by the treatment and the incidence of metropathies was unchanged.

Response to steroid therapy in autism secondary to autoimmune lymphoproliferative syndrome

We report a child who developed autoimmune lymphoproliferative syndrome (ALPS) secondary to a heterozygous dominant negative mutation in the death domain of the Fas receptor. Previously developmentally normal, he had symptoms of autism with rapid regression in developmental milestones coincident with the onset of lymphoproliferation and autoimmune hemolytic anemia. Low-dose steroid therapy induced early and complete remission in the ALPS phenotype. There was subjective improvement, followed by objective improvement in speech and developmental milestones. We propose that autism may be part of the autoimmune disease spectrum of ALPS in this child, and this case represents a novel manifestation and target organ involvement in this disease.

Massive cerebral embolization: successful treatment with retrograde perfusion

Stroke is an unpredictable and morbid complication of cardiac operations. We report a patient who suffered massive bilateral cerebral embolization during aortic cannulation for coronary bypass. This was treated successfully with hypothermic circulatory arrest and high flow retrograde cerebral perfusion. The patient suffered only minimal neurologic impairment and improved rapidly. She was discharged home on postoperative day 7 neurologically intact.

Turkey cytochrome c oxidase contains subunit VIa of the liver type associated with low efficiency of energy transduction

Cytochrome c oxidase was isolated from turkey liver, heart and breast skeletal muscle and separated by SDS/PAGE. The N-terminal amino-acid sequence of subunit VIa from all tissues and internal sequences from the skeletal muscle enzyme show homology to the mammalian liver-type subunit VIaL, which was verified by isolation and sequencing of the cDNA of turkey subunit VIa. No cDNA corresponding to subunit VIaH (mammalian heart-type) could be found by RACE-PCR with mRNA from all turkey tissues. Measurement of proton translocation with the reconstituted enzymes from turkey liver and heart revealed H+/e- ratios below 0.5 that were independent of the intraliposomal ATP/ADP ratio, as previously found with the bovine liver enzyme. Under identical conditions, the bovine heart enzyme revealed H+/e- ratios of 0.85 at low and 0.48 at high intraliposomal ATP/ADP ratios. The results suggest that in birds the lower H+/e-ratio of cytochrome c oxidase participates in elevated resting metabolic rate and thermogenesis.

Ictal SPECT hyperperfusion reflects the activation of the symptomatogenic cortex in spontaneous and electrically-induced non-habitual focal epileptic seizures: correlation with subdural EEG recordings

We report a patient with left temporal lobe epilepsy and a left parietal angioma, in whom ictal SPECT showed hyperperfusion in a spontaneous and an electrically-induced, non-habitual focal seizure. A SPECT investigation during an habitual seizure originating in the left temporal lobe showed a left temporal hyperperfusion. Electrical stimulation of the parietal cortex adjacent to the location of a previously resected angioma using subdural electrodes resulted in a non-habitual seizure beginning with a unilateral somatosensory aura. Ictal SPECT of this seizure demonstrated contralateral central hyperperfusion. We conclude from our findings that ictal SPECT hyperperfusion reflects the activation of symptomatogenic cortex, which can be induced by both epileptic discharge and electrical stimulation.

Studies of interaural attenuation to investigate the validity of a dichotic difference tone response recorded from the inferior colliculus in the chinchilla

In a previous paper (Arnold and Burkard, 1998) a dichotic f2-f1 difference tone (DT) auditory evoked potential from the chinchilla inferior colliculus (IC) was measured while presenting f1 (2000 Hz) to one ear and f2 (2100 Hz) to the other ear. This measurement paradigm could be used as a means to study binaural processing in an unanesthetized animal model. However, it is possible that this response is actually generated peripherally, as a result of acoustic crossover. The purpose of the present set of experiments was to investigate whether the dichotic DT is a true binaural phenomenon. Recordings were made from chronically implanted IC electrodes in unanesthetized, monaural chinchillas (left cochlea destroyed). In experiment 1, interaural attenuation (IA) was measured in two ways. First, IA was measured by comparing IC evoked potential thresholds obtained when stimulating the normal right ear and the dead left ear, using tone bursts (0.5-8 kHz). Mean values of interaural attenuation ranged from 50-65 dB across frequency (55 dB at 2000 Hz). Next, the DT was measured monaurally using f1 = 2000 and f2 = 2100 (L1 = L2). By comparing the mean DT input/output functions for monaural stimulation of the right and left ears, a mean value of IA for the tonal pair was estimated (approximately 69 dB). In experiment 2, the DT was measured with right monaural stimulation, while varying the relative levels of the primaries. A small DT could be seen with primary levels up to 30 dB apart, but not for greater level differences. Differences substantially greater than 30 dB would be expected in the crossover situation based upon IA. In experiment 3, the stimuli were presented dichotically (f1 to right ear, f2 to left ear and vice versa, L1 = L2) to determine whether acoustic crosstalk to the normal right ear would generate a DT. No DT was reliably observed in this condition. Taken together, these results suggest that the dichotic DT is a true binaural phenomenon, and not simply attributable to acoustic crossover.

The significance of preformed aprotinin-specific antibodies in cardiosurgical patients

Acute hypersensitivity reactions are serious complications of reexposure to aprotinin. Previous contact via infusions or fibrin tissue adhesives can induce specific antibodies. In this study, we aimed to elucidate the preoperative prevalence of aprotinin-specific antibodies in patients scheduled for cardiac operations. Sera of 520 consecutive cardiosurgical patients were collected preoperatively and screened retrospectively for aprotinin-specific IgG using a standard enzyme-linked immunosorbent assay (ELISA). Positive sera were analyzed also for aprotinin-specific IgA (ELISA) and IgE (fluorescence enzyme immunoassay). The histories of all patients were reviewed with focus on aprotinin preexposure. Of 520 patients, 22 (4%) had specific IgG. Only three of these had a documented aprotinin preexposure. Of 448 patients exposed to aprotinin intraoperatively, 15 had preformed specific antibodies. The only patient presenting with severe anaphylaxis was positive for both IgG and IgE, and had a recent IV preexposure in cardiovascular surgery. The presence of aprotinin-specific IgG alone seems not to induce adverse reactions on exposure. Exposure history alone is not sensitive enough to identify patients with aprotinin-specific antibodies.

IMPLICATIONS

Anaphylaxis on IV reexposure to aprotinin is a medical emergency. The clinical significance of preformed aprotinin-specific IgG remains questionable, whereas preformed IgE was present in the only patient who suffered from severe anaphylaxis on reexposure to aprotinin. Preformed antibodies are not reliably predicted by exposure history.

Childhood sexual abuse and dating experiences of undergraduate women

Child sexual abuse is a prevalent social problem with a variety of negative consequences for adult survivors. Whereas most studies have focused on intrapersonal effects including depressive symptomatology and post-traumatic stress disorder, recent work has begun to call attention to interpersonal results as well. The current study examined the relationship between the experience of childhood sexual abuse and being a victim of psychological aggression, physical violence, or sexual coercion in a dating relationship in the past year. Participants were 219 female college undergraduates. Child sexual abuse was significantly related to having experienced both physical and psychological dating aggression even after controlling for the presence of conflict in the family of origin. Child sexual abuse was not significantly related to sexual coercion or reports of silencing oneself in relationships.

Palmoplantar hyperkeratosis in Irish terriers: evidence of autosomal recessive inheritance

An abnormal development of the epidermis of the footpad was observed in Irish terriers. At the age of six months, the affected animals developed smooth parchment-like footpads. The pad epidermis then hardened and grew lateral cone-like protrusions of up to 5 mm in diameter. Fissures and cracks developed and these predisposed the animal to secondary infection. The repeated occurrence in subsequent generations led to the assumption of a hereditary form of hyperkeratosis. Evidence for an autosomal recessive mode of inheritance was derived from a retrospective analysis of the breeder's records. The clinical, histopathological and ultrastructural features of the disease are presented and the genetic transmission and its implications discussed.

A multicenter investigation with D-FISH BCR/ABL1 probes

Twenty-eight laboratories evaluated a new fluorescence in situ hybridization (FISH) strategy for chronic myeloid leukemia. In a three-part study, bcr/abl1 D-FISH probes were used to study bone marrow specimens. First, laboratories familiarized themselves with the strategy by applying it to known normal and abnormal specimens. Then, collectively the laboratories studied 20 normal and 20 abnormal specimens blindly and measured workload. Finally, each laboratory and two experts studied six serial dilutions with 98-0% abnormal nuclei. Using the reported normal cutoff of < 1% abnormal nuclei, participants reported no false-negative cases and 15 false-positive cases (1-6.6% abnormal nuclei). Results provided by participants for serial dilutions approximated the expected percentages of abnormal nuclei, but those from the experts exhibited greater precision. The clinical sensitivity, precision, nomenclature, workload, recommendations for training, and quality assurance in methods using D-FISH in clinical practice are discussed.

[Noninvasive protocol for surgical treatment of focal epilepsies]

We present a non-invasive epilepsy surgery protocol, which includes EEG-video-monitoring, magnetic resonance imaging (MRI), interictal positron emission tomography (PET) and ictal single photon emission computerized tomography (SPECT). According to this non-invasive protocol 50 of 173 patients with medically intractable focal epilepsy underwent resective surgery. The localization of the epileptogenic zone was based on the congruence of the localizing results of EEG-video-monitoring, MRI, interictal PET and ictal SPECT. 46 (92%) of the patients had temporal and 4 (8%) had extratemporal epilepsies. 78% (n = 39) of all patients operated according to our non-invasive protocol were postoperatively completely or almost seizure free. Extramesiotemporal resections could be carried out without invasive EEG-recording if the epileptogenic zone was not adjacent to the eloquent cortex. We conclude from our results that in a considerable number of patients with medically intractable particularly temporal focal epilepsies, resective epilepsy surgery can be based on non-invasive EEG-evaluations and the risk of invasive recordings can be avoided.

The two subunits of the interleukin-4 receptor mediate independent and distinct patterns of ligand endocytosis

Interleukin-4 (IL-4) triggers cellular responses by interaction with the bipartite interleukin-4 receptor (IL-4R). IL-4-responsive cells specifically endocytose IL-4. We studied the ligand internalization properties of the human IL-4R and analyzed the specific functions of its two subunits IL-4Ralpha and gammac in this process. IL-4 mutant RY, which binds to IL-4Ralpha but does not recruit gammac into the receptor complex was used as a tool to show that IL-4Ralpha can promote independent ligand uptake in human T cells. Internalization was limited, however, by rapid IL-4 dissociation, suggesting that one important function of gammac in IL-4 endocytosis is to retain the ligand sufficiently long within the ternary receptor complex. We then measured IL-4 internalization by murine Ba/F3 cells that were stably transfected with various human IL-4R constructs. Efficient IL-4 uptake required the cytoplasmic section of the receptor. The intracellular domains of IL-4Ralpha and gammac were responsible for independent endocytosis processes with distinct kinetics. IL-4Ralpha-mediated internalization resulted in long-term intracellular maintainance of IL-4, whereas gammac directed the associated radioligand to intracellular breakdown and rapid release in the form of degraded protein. Mutants of either IL-4R subunit deficient in Janus kinase activation were not impaired in internalization, indicating that IL-4 endocytosis is not functionally connected to signal transduction.

Bilateral reductions of hippocampal volume, glucose metabolism, and wada hemispheric memory performance are related to the duration of mesial temporal lobe epilepsy

In refractory temporal lobe epilepsy (TLE) temporal lobe structures and functions are continuously or intermittently affected by abnormal brain electrical events, noxious neurochemical agents, and metabolic disturbances. There is conflicting evidence regarding the relationship between the duration of refractory mesial TLE and quantitative measures of temporal lobe functions and volumes of the hippocampi. Twenty patients (aged 28 +/- 7 years, 14 males) with an initial precipitating injury before the age of 5 years were subjected to high-resolution magnetic resonance imaging, fluoro-2-deoxy-d-glucose positron-emission tomography (PET), and the Wada test. We investigated whether the duration of unilateral refractory TLE (12 left, 8 right) affects hippocampal volume, glucose metabolism, or Wada hemispheric memory performance. Ipsilateral to the epileptogenic zone the hippocampal volume, metabolism, and Wada hemispheric memory performance were reduced compared to the corresponding contralateral measures. The duration of epilepsy controlled for age at investigation, side of seizure origin, underlying cause, and sex were negatively correlated with ipsi- and contralateral hippocampal volume, hippocampal metabolism, and Wada hemispheric memory performance. Moreover, ipsilateral Wada hemispheric memory performance and contralateral hippocampal glucose metabolism were correlated with the frequency of habitual seizures. Refractory TLE seems to be associated with a slow but ongoing bilateral temporal lobe damage. These cross-sectional results require verification by longitudinal studies carried out over a period of more than two decades.

Quantitative electron spectroscopic diffraction analyses of the crystal formation in dentine

Newly formed apatitic crystallites of different hard tissues consist, according to our investigations, of chains composed of nanometre-sized particles (islands, dots) arising at nucleating sites of the collagenous and noncollagenous matrix macromolecules. In dentine these islands coalesce rapidly in longitudinal direction to form needle-like crystallites which further coalesce to ribbon-like crystallites. We have concluded that the centre-to-centre distances between these islands represent the distances between the nucleating sites of the matrix macromolecules. We have applied energy-filtering transmission electron microscopy in the selected area electron diffraction mode at different stages of crystal formation in dentine and have obtained quantitative information of the degree of crystal disorder on the basis of the paracrystal theory. The fluctuation of the lattice plane distances in c-axis direction decreases, proceeding from the region near the dentine/predentine border to the dentine/enamel border.

Reorganized cerebral metabolic interactions in temporal lobe epilepsy

Patients with left temporal lobe epilepsy demonstrate language impairments that are not well understood. To explore abnormal patterns of brain functional connections with respect to language processing, we applied a principal component analysis to resting regional cerebral metabolic data obtained with positron emission tomography in patients with right- and left-sided temporal lobe epilepsy and controls. Two principal components were expressed differentially among the groups. One principal component comprised a pattern of metabolic interactions involving left inferior frontal and left superior temporal regions-corresponding to Broca's and Wernicke's areas, respectively-and right mesial temporal cortex and right thalamus. Functional couplings between these brain regions were abnormally enhanced in the left-sided epilepsy patients. The right thalamic left superior temporal coupling was also abnormally enhanced in the right-sided epilepsy patients, but differentially from that in the left-sided patients. The other principal component was characterized by a pattern of metabolic interactions involving right and left mid prefrontal and right superior temporal cortex. Although both the right- and left-sided epilepsy patients showed decreased functional couplings between left mid prefrontal and the other brain regions, a weaker right-left mid prefrontal coupling in the left-sided epilepsy patients best distinguished them from the right-sided patients. The two mutually independent, abnormal metabolic patterns each predicted verbal intelligence deficits in the patients. The findings suggest a site-dependent reorganization of two independent, language-subserving pathways in temporal lobe epilepsy.

Sry-negative XX true hermaphrodite in a Basset hound

A true hermaphrodite was diagnosed in a 7-mo.-old Basset hound. The diagnosis was based on the clinical signs, the histology of the gonads and the karyogram. Additionally, the dog was tested for the Y-linked gene Sry, which was negative. The Basset hound presented here is compared to other XX sex reversed animals described in the literature. In man, XX sex reversal is a heterogenous condition. The pathogenesis in Sry-negative individuals is not understood. Thus Sry-negative animals could serve as an animal model of the human disease.

18F-FDG PET studies in patients with extratemporal and temporal epilepsy: evaluation of an observer-independent analysis

The aim of this study was to evaluate an observer-independent analysis of 18F-fluorodeoxyglucose (FDG) PET studies in patients with temporal or extratemporal epilepsy.

METHODS

Twenty-seven patients with temporal epilepsy and 22 patients with extratemporal epilepsy were included in the study. All patients with temporal epilepsy and 7 patients with extratemporal epilepsy underwent surgical treatment. In patients who showed significant postoperative improvement (temporal, n = 23; extratemporal, n = 6), the epileptogenic focus was assumed to be located in the area of surgical resection. In extratemporal epilepsy patients who did not undergo surgery, the focus localization was determined using a combination of semiology, ictal and interictal electroencephalography, [99mTc]ethyl cysteinate dimer SPECT, MRI and [11C]flumazenil PET. Visual analysis was performed by two experienced and two less experienced blinded observers using sagittal, axial and coronal images. In the automated analysis after anatomic standardization and generation of three-dimensional stereotactic surface projections (SSPs), a pixelwise comparison of 18F-FDG uptake with an age-matched reference database (n = 20) was performed, resulting in z score images. Pixels with the maximum deviation were detected, summarized and attached to one of 20 predefined surface regions of interest. For comparison with 18F-FDG PET and MR images, three-dimensional overlay images were generated.

RESULTS

In patients with temporal epilepsy, the sensitivity was comparable for visual and observer-independent analysis (three-dimensional SSP 86%, experienced observers 86%-90%, less experienced observers 77%-86%). In patients with extratemporal epilepsy, three-dimensional SSP showed a significantly higher sensitivity in detecting the epileptogenic focus (67%) than did visual analysis (experienced 33%-38%, each less experienced 19%). In temporal lobe epilepsy, there was moderate to good agreement between the localization found with three-dimensional SSP and the different observers. In patients with extratemporal epilepsy, there was a high interobserver variability and only a weak agreement between the localization found with three-dimensional SSP and the different observers. Although three-dimensional SSP detected multiple lesions more often than visual analysis, the determination of the highest deviation from the reference database allowed the identification of the epileptogenic focus with a higher accuracy than subjective criteria, especially in extratemporal epilepsy.

CONCLUSION

Three-dimensional SSP increases sensitivity and reduces observer variability of the analysis of 18F-FDG PET images in patients with extratemporal epilepsy and is, therefore, a useful tool in the evaluation of this patient group. The benefit of this analytical approach in patients with temporal epilepsy is less apparent.

E-cadherin binding prevents beta-catenin nuclear localization and beta-catenin/LEF-1-mediated transactivation

Beta-catenin is a multifunctional protein found in three cell compartments: the plasma membrane, the cytoplasm and the nucleus. The cell has developed elaborate ways of regulating the level and localization of beta-catenin to assure its specific function in each compartment. One aspect of this regulation is inherent in the structural organization of beta-catenin itself; most of its protein-interacting motifs overlap so that interaction with one partner can block binding of another at the same time. Using recombinant proteins, we found that E-cadherin and lymphocyte-enhancer factor-1 (LEF-1) form mutually exclusive complexes with beta-catenin; the association of beta-catenin with LEF-1 was competed out by the E-cadherin cytoplasmic domain. Similarly, LEF-1 and adenomatous polyposis coli (APC) formed separate, mutually exclusive complexes with beta-catenin. In Wnt-1-transfected C57MG cells, free beta-catenin accumulated and was able to associate with LEF-1. The absence of E-cadherin in E-cadherin-/- embryonic stem (ES) cells also led to an accumulation of free beta-catenin and its association with LEF-1, thereby mimicking Wnt signaling. beta-catenin/LEF-1-mediated transactivation in these cells was antagonized by transient expression of wild-type E-cadherin, but not of E-cadherin lacking the beta-catenin binding site. The potent ability of E-cadherin to recruit beta-catenin to the cell membrane and prevent its nuclear localization and transactivation was also demonstrated using SW480 colon carcinoma cells.

Investigation of translation dynamics under cell-free protein biosynthesis conditions using high-resolution two-dimensional gel electrophoresis

A cell-free extract from Escherichia coli, generated through a routine procedure according to Chen and Zubay (Methods Enzymol. 1983, 101, 674-690), was used for an in vitro protein synthesis. High-resolution two-dimensional gel electrophoresis (2-DE) was exploited to investigate the protein composition of the cell-extract and its dynamic development during a 24 h-period of cell-free protein synthesis performed in a membrane reactor device. Green fluorescent protein (GFP) was chosen as a target protein to be produced in a cell-free reactor because of its functional activity, which can easily be monitored by measurement of fluorescence, and because of its high sensitivity. GFP synthesis was observed by a standard fluorescence assay and was correlated to a quantitative assessment of the silver-stained GFP spot appearing on 2-DE gel maps. A constant protein synthesis rate was obtained for at least 8 h of process operation. While declining continuously, protein synthesis stopped entirely after 24 h. Both, the total protein content and total number of detectable spots were found to decrease over the reaction time, due to proteolytic digestion and protein precipitation. Certain proteins taking part in the translation process, such as the elongation factors (EF-Tu, EF-Ts) and the ribosomal protein RP-L9, were identified by Edman N-terminal sequencing and have thus been considered for reaction evaluation. The dynamics obtained during the entire process suggest that these translational factors were likewise affected by proteolytic decay.

A second mechanism of respiratory control

According to the chemosmotic hypothesis, ATP is synthesized in mitochondria, bacteria and chloroplasts via the proton motive force delta p, the energy-rich intermediate of electron transport and photosynthetic phosphorylation. The general applicability of the chemosmotic hypothesis, however, was disputed until present. In particular the relationship between the rate of respiration and delta p in mitochondria was found variable, depending on the experimental conditions. Recently, a new mechanism of respiratory control was found, based on binding of ATP or ADP to subunit IV of cytochrome c oxidase, which is independent of delta p and could explain many previous results contradicting the chemosmotic hypothesis.

MR measurement of regional relative cerebral blood volume in epilepsy

The purpose of this study was to evaluate the utility of magnetic resonance (MR) relative cerebral blood volume (rCBV) maps for studying regional hemodynamic changes in interictal and ictal epilepsy patients. Ten epilepsy patients were examined on a 1.5 T MR system. Nine patients were investigated interictally and one patient ictally. In the nine interictal patients, the dynamic plane was defined coronally through the hippocampus symmetrically. For the ictal patient, an axial dynamic plane was defined and the patient was scanned during seizure. Positron emission tomography (PET) studies were performed in 8 of the 10 patients. Lower rCBV of the left hippocampus was predicted by rCBV maps in seven of the nine interictal patients. The mean ratios of rCBV were 1.96 for left hippocampus/white matter and 2.49 for right hippocampus/white matter. The difference between these two ratios is statistically significant (P = 0.01, t-test). In two of the nine interictal temporal lobe epilepsy patients, lower rCBV areas were observed in the right hippocampus. In the ictal patient, the regional rCBV map demonstrated increased blood volume in the lesions. In eight of eight patients who underwent PET studies, MR rCBV findings were consistent with PET findings. The results show that regional hemodynamic changes in epilepsy can be evaluated with dynamic contrast-enhanced MR imaging. MR rCBV maps are sensitive to characterize seizure foci both ictally and interictally.

The intramitochondrial ATP/ADP-ratio controls cytochrome c oxidase activity allosterically

Recently the signal transduction function for oxidative phosphorylation was found to be second order in ADP [Jeneson, J.A.L., Wiseman, R.W., Westerhoff, H.V. and Kushmerick, M.J. (1996) J. Biol. Chem. 271, 27995-279981, but the molecular mechanism of signal transduction remained unclear. Previously we described inhibition of cytochrome c oxidase by intramitochondrial ATP, accompanied by a change of hyperbolic into sigmoidal kinetics. The present study describes a sigmoidal relationship also between the ascorbate respiration of reconstituted cytochrome c oxidase and intraliposomal ADP concentration. Its possible role in the control of oxidative phosphorylation and cell respiration is discussed.

Extracellular ATP causes apoptosis and necrosis of cultured mesangial cells via P2Z/P2X7 receptors

Mesangial cells undergo cell death both by apoptosis and necrosis during glomerular disease. Since nucleotides are released from injured and destroyed cells in the glomerulus, we examined whether extracellular ATP and its receptors may regulate cell death of cultured mesangial cells. Addition of extracellular ATP (300 microM to 5 mM) to cultured rat mesangial cells for 90 min caused a 5. 8-fold increase in DNA fragmentation (terminal deoxynucleotidyl transferase assay) and a 4.2-fold increase in protein levels of the tumor suppressor p53, which is thought to regulate apoptosis. Apoptotic DNA fragmentation was confirmed by the diphenylamine assay and by staining with the DNA-specific fluorochrome Hoechst 33258. The necrotic markers, release of lactate dehydrogenase and uptake of trypan blue, were not positive before 3 h of ATP addition. The effects of ATP on DNA fragmentation and p53 expression were reproduced by the purinergic P2Z/P2X7 receptor agonist, 3'-O-(4-benzoylbenzoyl)-ATP, and inhibited by the P2Z/P2X7 receptor blocker, oxidized ATP. Transcripts encoding the P2Z/P2X7 receptor were expressed by cultured mesangial cells as determined by Northern blot analysis. P2Z/P2X7 receptor-associated pore formation in the plasma membrane was demonstrated by the Lucifer yellow assay. We conclude that activation of P2Z/P2X7 receptors by extracellular ATP causes apoptosis and necrosis of cultured mesangial cells. Activation of purinergic P2Z/P2X7 receptors may play a role in causing death of mesangial cells during glomerular disease.

Antibiotic-resistant Streptococcus pneumoniae. Implications for medical practice

OBJECTIVE

To review the definition and prevalence of antibiotic-resistant Streptococcus pneumoniae, its links with antibiotic prescribing, data on antibiotic prescribing and prescribing appropriateness, and evidence-based treatment guidelines for common respiratory tract syndromes.

QUALITY OF EVIDENCE

Primary studies consist of cross-sectional surveys and case-control studies. Treatment guidelines are based on clinical trials, meta-analyses, and cohort studies. Study designs were appropriate for the specific study questions.

MAIN FINDINGS

The increasing prevalence of penicillin-resistant S pneumoniae is concurrent with increasing antibiotic prescribing. Individual patients show a twofold to ninefold increase in nasopharyngeal carriage of resistant bacteria or invasion with resistant bacteria (among those who have received antibiotics in the preceding 3 months). Cross-sectional data as well as data from medicaid and drug databases attest to overprescribing of antibiotics for respiratory tract infections. Physician surveys and focus groups blame this on parental pressure for antibiotic prescriptions. However, parents in focus groups and surveys deny they pressure their physicians and indicate their main purpose for office visits is to obtain a diagnosis and to seek reassurance that their children are not seriously ill. Evidence-based guidelines suggest treatment strategies that would reduce antibiotic prescribing.

CONCLUSIONS

The few antibiotics that can be used with resistant organisms are expensive and are increasingly being needed. To control the rise of antibiotic resistance, it is important to limit antibiotic overprescribing.

The auditory evoked potential difference tone and cubic difference tone measured from the inferior colliculus of the chinchilla

The auditory evoked potential f2-f1 difference tone (DT) and the 2 f1-f2 cubic difference tone (CDT) were recorded from electrodes implanted in the inferior colliculus in a group of chinchillas. The purpose of this study was to measure normative aspects of AEP distortion products in awake chinchillas, by comparing the DT and CDT under a variety of stimulus conditions. For experiment 1, f1 was held constant at 1998 Hz, while the f2/f1 ratio was varied from 1.05 to 1.50. Input-output functions were measured over a range of primary tone levels up to 80 dB SPL. The amplitude of the DT was greatest for the smallest f2/f1 ratio, and decreased systematically as f2/f1 ratio increased. DT amplitude was greater than CDT amplitude for all primary tone pairs. Experiment 2 was conducted to determine the effect of f1 frequency upon the DT and CDT for a constant f1-f2 difference frequency of 102 Hz (f1-999, 1998, 4999, and 9998 Hz). The DT input-output functions were overlapping for all f1 frequencies. For the CDT, amplitude decreased with increasing f1 frequency, which corresponded to an increase in CDT frequency. In experiment 3, the relationship between ear of stimulation and inferior colliculus recorded from was investigated. DT input-output functions (f1 = 1998 Hz, DT = 102 Hz) were measured for monaural contralateral, monaural ipsilateral, and dichotic stimulus conditions. DT amplitude was largest for the contralateral condition, followed by the ipsilateral condition. A smaller, dichotic component to the DT was observed as well.

[Solar glossitis in sled dogs]

In a colony of sledge dogs, an increased incidence of ulcerative glossitis was diagnosed. Several facts indicate that the lesions were directly caused by UV light. The presence of signs coincided with the use of the dogs of the glacier. The lesions were localized on the first part of the tongue. The histologic changes were consistent with a phototoxic reaction and other causes of glossitis were ruled out.

Cytochrome c oxidase from eucaryotes but not from procaryotes is allosterically inhibited by ATP

The activity of reconstituted cytochrome c oxidase from bovine heart but not from Rhodobacter sphaeroides is allosterically inhibited by intraliposomal ATP, which binds to subunit IV. The activity of cytochrome c oxidase of wild-type yeast and of a subunit VIa-deleted yeast mutant, measured with Tween 20-solubilized mitochondria in the presence of an ATP-regenerating system, was also allosterically inhibited by ATP, indicating the general validity of this mechanism of "respiratory control" in eucaryotic cytochrome c oxidases (Arnold and Kadenbach, Eur. J. Biochem. (1997) 249, 350-354). Deletion of subunit VIa changes the biphysic into monophysic kinetics of the yeast enzyme in the presence of ADP. A tenfold higher amount of horse heart cytochrome c, as compared to yeast cytochrome c, was required to relieve the ATP inhibition of the yeast enzyme.

A multicenter investigation with interphase fluorescence in situ hybridization using X- and Y-chromosome probes

Twenty-six laboratories used X and Y chromosome probes and the same procedures to process and examine 15,600 metaphases and 49,400 interphases from Phaseolus vulgaris-leucoagglutinin (PHA)-stimulated lymphocytes. In Part I, each laboratory scored 50 metaphases and 200 interphases from a normal male and a normal female from its own practice. In Part II, each laboratory scored 50 metaphases and 200 interphases on slides prepared by a central laboratory from a normal male and a normal female and three mixtures of cells from the male and female. In Part III, each laboratory scored 50 metaphases (in samples of 5, 10, 15, and 20) and 100 interphases (in samples of 5, 10, 15, 20, and 50) on new, coded slides of the same specimens used in Part II. Metaphases from male specimens were scored as 98-99% XY with no XX cells, and 97-98% of interphases were scored as XY with 0.04% XX cells. Metaphases from female specimens were scored as 96-97% XX with 0.03% XY cells, and 94-96% of interphases were scored as XX with 0.05% XY cells. Considering the data as a model for any probe used with fluorescence in situ hybridization (FISH), a statistical approach assessing the impact of analytical sensitivity on the numbers of observations required to assay for potential mosaicisms and chimerisms is discussed. The workload associated with processing slides and scoring 50 metaphases and 200 interphases using FISH averaged 27.1 and 28.6 minutes, respectively. This study indicates that multiple laboratories can test/develop guidelines for the rapid, efficacious, and cost-effective integration of FISH into clinical service.

Chromosomal assignment of two putative canine keratin gene clusters

Mutations in keratin genes account for a number of inherited keratodermas in humans. The groups of basic and acidic keratin genes are clustered on human chromosomes 12 and 17, respectively. The present authors have assigned the two putative keratin gene clusters to canine chromosomes using canine cosmid clones. Successful fluorescence in situ hybridization mapped the putative cluster of canine acidic genes to dog chromosome 20 and the putative cluster of basic keratin genes to a small autosome not yet included in the partial canine standard karyotype.

3,5-Diiodothyronine binds to subunit Va of cytochrome-c oxidase and abolishes the allosteric inhibition of respiration by ATP

The short-term effects of thyroid hormones, which do not occur via gene expression, were postulated to be based on interaction of diiodothyronines with mitochondria. We demonstrate specific binding of labelled 3,5-diiodothyronine to subunit Va of cytochrome-c oxidase from bovine heart. 3,5-Diiodothyronine, and to a small extent triiodothyronine, but not thyroxine and thyronine, abolish the allosteric inhibition of ascorbate respiration of reconstituted cytochrome c oxidase by ATP [Arnold, S. & Kadenbach, B. (1997) Eur. J. Biochem. 249, 350-354]. This abolition of ATP-inhibition by 3,5-diiodothyronine is completely prevented by a monoclonal antibody to subunit Va. The results explain at the molecular level the short-term action of thyroid hormones on basal metabolic rate.

[Semiologic classification of epileptic seizures]

Recent advances in epileptology and epilepsy surgery require revision of the currently used International Classification of Epileptic Seizures, which was published 1981. We present a classification of epileptic seizures which is based purely on the clinical seizure semiology. The advantages of a semiological seizure classification are stressed.

Ictal technetium-99m ethyl cysteinate dimer single-photon emission tomographic findings and propagation of epileptic seizure activity in patients with extratemporal epilepsies

Although ictal single-photon emission tomography (SPET) with technetium-99m ethyl cysteinate dimer (ECD) has a well-established role in the diagnostic evaluation of patients with temporal lobe epilepsy who are being considered for epilepsy surgery, its use in cases of extratemporal epilepsy is still limited. We investigated the influence of the propagation of extratemporal epileptic seizure activity on the regional increase in cerebral blood flow, which is usually associated with epileptic seizure activity. Forty-two consecutive patients with extratemporal epilepsies were prospectively evaluated. All patients underwent ictal SPET studies with simultaneous electroencephalography (EEG) and video recordings of habitual seizures and imaging studies including cranial magnetic resonance imaging and positron emission tomography with 2-[18F]-fluoro-2 deoxy-d-glucose. Propagation of epilptic seizure activity (PESA) was defined as the absence of hyperperfusion on ictal ECD SPET in the lobe of seizure onset, but its presence in another ipsilateral or contralateral lobe. Observers analysing the SPET images were not informed of the other results. PESA was observed in 8 of the 42 patients (19%) and was ipsilateral to the seizure onset in five (63%) of these eight patients. The time between clinical seizure onset and injection of the ECD tracer ranged from 14 to 61 s (mean 34 s). Seven patients (88%) with PESA had parieto-occipital epilepsy and one patient had a frontal epilepsy. PESA was statistically more frequent in patients with parieto-occipital lobe epilepsies (58%) than in the remaining extratemporal epilepsy syndromes (3%) (P<0.0002). These findings indicate that ictal SPET studies require simultaneous EEG-video recordings in patients with extratemporal epilepsies. PESA should be considered when interpreting ictal SPET studies in these patients. Patients with PESA are more likely to have parieto-occipital lobe epilepsy than seizure onset in other extratemporal regions.

Regulation of energy transduction and electron transfer in cytochrome c oxidase by adenine nucleotides

Cytochrome c oxidase from bovine heart contains seven high-affinity binding sites for ATP or ADP and three additional only for ADP. One binding site for ATP or ADP, located at the matrix-oriented domain of the heart-type subunit VIaH, increases the H+/e- stoichiometry of the enzyme from heart or skeletal muscle from 0.5 to 1.0 when bound ATP is exchanged by ADP. Two further binding sites for ATP or ADP, located at the cytosolic and the matrix domain of subunit IV, increases the K(M) for cytochrome c and inhibit the respiratory activity at high ATP/ADP ratios, respectively. We propose that thermogenesis in mammals is related to subunit VIaL of cytochrome c oxidase with a H+/e- stoichiometry of 0.5 compared to 1.0 in the enzyme from bacteria or ectotherm animals. This hypothesis is supported by the lack of subunit VIa isoforms in cytochrome c oxidase from fish.

[Urinary incontinence in castrated bitches. Part 1: Significance, clinical aspects and etiopathogenesis]

Acquired urinary incontinence occurs in 20% of spayed dogs and there exists a strong correlation between body weight and the risk of urinary incontinence. Bitches with a body weight of more than 20 kg have a risk of 30% white smaller dogs have a risk of 10%. A particular breed disposition exists in Boxers in which 65% are affected. Other breeds with a more than average disposition for urinary incontinence are Dobermans and Giant Schnauzers. Urinary incontinence due to spaying manifests itself mainly while the dogs are sleeping. The cause is a urethral sphincter incompetence which can be verified by a urethral pressure profile (UPP). The microtransducer method proved to be a suitable method for urodynamic studies. It could be demonstrated that the urethral closure pressure is significantly lower in incontinent bitches (4.6 +/- 2.3 cm H2O) than in continent bitches (18.6 +/- 10.5 cm H2O). In addition, the urethral closure pressure for continent bitches dropped significantly within 12 months after surgery. Histological examination revealed that the functional urethral closure cannot be explained by the extent of discernible structures of the urethral wall as seen by light microscopy.

Analysis of a general principle of crystal nucleation, formation in the different hard tissues

We have found, at high EM magnification, on ultrathin sections of shock-frozen, freeze-dried, embedded pieces of the developing hard tissues, that the primary crystallites consist of strands composed of nanometer-sized apatitic islands, which rapidly coalesce to needles and afterward to platelets. By small-area electron diffraction, with energy-filtered electrons, it was clarified that these strands are already crystallographically oriented along the bipolar c-axis so that the center-to-center distances between the islands would reflect the distances between crystal-nucleating sites along the matrix. The EM analysis of the cross-cut stained unmineralized and of the unstained mineralized collagen fibers of turkey tibia tendon shows that the staining "nuclei" and the early crystallites, appearing as dark dots, surround "light" round structures, which we interpret as the collagen microfibrils, surrounded by the apatitic crystallites.

Cell respiration is controlled by ATP, an allosteric inhibitor of cytochrome-c oxidase

The activity of cytochrome-c oxidase, the terminal enzyme of the mitochondrial respiratory chain, is known to be regulated by the substrate pressure, i.e. the ferro-/ferricytochrome c ratio, by the oxygen concentration, and by the electrochemical proton gradient delta muH+ across the inner mitochondrial membrane. Here we describe a further mechanism of 'respiratory control' via allosteric inhibition of cytochrome-c oxidase by ATP, which binds to the matrix domain, of subunit IV. The cooperativity between cytochrome-c-binding sites in the dimeric enzyme complex is mediated by cardiolipin, which is essential for cooperativity of the enzyme within the lipid membrane.

Cavity-mode selection in spontaneous emission from oriented molecules in a microparticle

We observe preferential cavity-mode selection in spontaneous emission by oriented molecules at the surface of a microparticle. Polarization-analyzed images of a levitated microdroplet containing surface active molecules reveal a well-defined system in terms of molecular position and orientation. The measured fluorescence spectrum is compared with that of a semiclassical emission-rate-enhancement model that treats the coupling between an excited state and Mie resonances as an oscillating dipole interacting with its self-scattered field. By comparing results obtained with this theory with the relative strengths of TE to TM modes measured in the emission spectrum, we show that one can elucidate the heterogeneity of a particle from this resonant structure and determine the orientation of the emission moments relative to the phase boundary.

The subunit structure of cytochrome-c oxidase from tuna heart and liver

Cytochrome-c oxidase was isolated from tuna liver and heart, and the subunit composition was analysed by SDS/PAGE by two separation systems. Two additional subunits of the enzyme complex were immunoprecipitated from solubilized mitochondria with an antibody against bovine subunit IV. The N-terminal and internal amino acid sequences of all nuclear-coded subunits were determined after blotting onto poly(vinylidene difluoride) membranes or by tryptic hydrolysis of gel bands and HPLC separation of peptides, respectively. 13 subunits were identified with isoforms for subunits Va, VIc, VIIb and VIII. The isoforms for subunits Va and VIIb are found in liver and heart, isoforms for subunit VIc only in heart, and isoforms for subunit VIII only in liver. Isoforms for subunits Va, VIc and VIIb have not been described in other species. The postulated mechanism of thermogenesis in mammals, based on decreased H+/e- stoichiometry at high ATP/ADP ratios due to binding of ATP to the heart-type subunit VIa [Frank, V. & Kadenbach, B. (1996) FEBS Lett. 382, 121-124], appears not to occur in tuna, because no isoforms of subunit VIa were found.