Reply to 'Dieulafoy's disease of the lung: a potential disaster for the bronchoscopist'.
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Biopsy↗
Biomedical subjects
Andreas Knoblauch
Publications and source records attributed to Andreas Knoblauch.
Molecular cytogenetic analysis of a de novo interstitial chromosome 10q22 deletion.
Interstitial deletions of 10q are rare, and only one patient with a deletion confined to chromosome band 10q22 has been reported so far. We report on a 2 6/12-year-old girl with a constitutional interstitial deletion of one homologue of 10q [karyotype: 46,XX,del(10)(q22.2q22.3)de novo]. Our patient had muscular hypotonia, developmental delay, growth retardation, mild facial dysmorphism, and hypoplastic labia minora. The precise location and extent (3.6 Mb) of the deletion was determined by fluorescence in situ hybridization (FISH) using 16 YAC and BAC clones. The clinical features in our patient are remarkably similar to the previously reported patient with a 10q22.2 deletion.
Abnormalities, Multiple↗
Molecular cytogenetic analysis of a de novo interstitial deletion of 5q23.3q31.2 and its phenotypic consequences.
We report a 2(3/12)-year-old boy with a constitutional interstitial deletion of 5q,46,XY,del(5)(q23.3q31.2) de novo. Clinical manifestations in this patient included failure to thrive, psychomotor retardation, mild facial dysmorphic features, and long and slender fingers and toes. The precise location and extent (9.5 Mb) of the deletion was determined by fluorescence in situ hybridization (FISH) using 19 YAC and BAC clones. Comparison of the present patient with six other patients with deletions of chromosomal bands 5q22-5q31 allowed further delineation of a constitutional del5q22q31 syndrome. The main features of this syndrome are psychomotor retardation, failure to thrive, hypotonia, hypoplastic muscles, cleft or high arched palate, low-set and dysplastic ears, flat nasal bridge, downslanting palpebral fissures, hypertelorism, anteverted nostrils, and micro- and/or retrognathia.
Abnormalities, Multiple↗
Dieulafoy's disease of the lung: a potential disaster for the bronchoscopist.
Dieulafoy's disease of the lung is very rare. We present 2 cases, which are, to our knowledge, the 9th and 10th cases reported in the literature. Haemoptysis is the leading symptom of Dieulafoy's lesion of the lung. In spite of its rareness, the lesion is relevant to the bronchoscopist because a biopsy of the unobtrusive but characteristic bronchial manifestation can precipitate profuse arterial bleeding with a fatal outcome. The bleeding can occur immediately after the biopsy and/or after an interval of up to 12 days. Angiographic images document that this vascular malformation is based on a left-to-right shunt, with a bronchial artery draining into a pulmonary artery. Endobronchial ultrasound may be helpful in detecting the vascular nature of the lesion.
Biopsy↗
Prediction of treatment-response to inhaled corticosteroids by mannitol-challenge test in COPD. A proof of concept.
BACKGROUND: There are no predictors known that can identify COPD patients who will respond to treatment with ICS. METHOD: We investigated 30 patients (median age 65 (range 44-83, 12 females) with mild to moderately severe COPD. All patients had post bronchodilator FEV1/forced vital capacity ratio of less than 70% and a reversibility of less than 12% and 200 ml from baseline. We wanted to determine if airway responsiveness (AHR) to histamine and mannitol could predict who would respond to a 3-month course of ICS. RESULTS: At baseline, all patients had AHR to histamine, but only 7 (23%) patients to mannitol. After 3 months of treatment with ICS, there was no significant change in spirometry or the quality of life when analysing all individuals together. However, FEV1% predicted improved from 67% (IQR12) to 79% (IQR16) in mannitol positive patients; whereas it was unchanged in the mannitol negative patients. The difference in the mean change of FEV1% predicted between the two groups was 12 (IQR13.5) and this was highly significant (p=0.001). The improvement in quality of life (SGRQ 30 (IQR10.5) to 21 (IQR12; p=0.01) was only significant in the patients positive to mannitol. CONCLUSION: We propose that AHR to mannitol could predict ICS-responsiveness in mild to moderately severe COPD patients.
Administration, Inhalation↗
Scene segmentation by spike synchronization in reciprocally connected visual areas. I. Local effects of cortical feedback.
To investigate scene segmentation in the visual system we present a model of two reciprocally connected visual areas using spiking neurons. Area P corresponds to the orientation-selective subsystem of the primary visual cortex, while the central visual area C is modeled as associative memory representing stimulus objects according to Hebbian learning. Without feedback from area C, a single stimulus results in relatively slow and irregular activity, synchronized only for neighboring patches (slow state), while in the complete model activity is faster with an enlarged synchronization range (fast state). When presenting a superposition of several stimulus objects, scene segmentation happens on a time scale of hundreds of milliseconds by alternating epochs of the slow and fast states, where neurons representing the same object are simultaneously in the fast state. Correlation analysis reveals synchronization on different time scales as found in experiments (designated as tower, castle, and hill peaks). On the fast time scale (tower peaks, gamma frequency range), recordings from two sites coding either different or the same object lead to correlograms that are either flat or exhibit oscillatory modulations with a central peak. This is in agreement with experimental findings, whereas standard phase-coding models would predict shifted peaks in the case of different objects.
Animals↗
Scene segmentation by spike synchronization in reciprocally connected visual areas. II. Global assemblies and synchronization on larger space and time scales.
We present further simulation results of the model of two reciprocally connected visual areas proposed in the first paper [Knoblauch and Palm (2002) Biol Cybern 87:151-167]. One area corresponds to the orientation-selective subsystem of the primary visual cortex, the other is modeled as an associative memory representing stimulus objects according to Hebbian learning. We examine the scene-segmentation capability of our model on larger time and space scales, and relate it to experimental findings. Scene segmentation is achieved by attention switching on a time-scale longer than the gamma range. We find that the time-scale can vary depending on habituation parameters in the range of tens to hundreds of milliseconds. The switching process can be related to findings concerning attention and biased competition, and we reproduce experimental poststimulus time histograms (PSTHs) of single neurons under different stimulus and attentional conditions. In a larger variant the model exhibits traveling waves of activity on both slow and fast time-scales, with properties similar to those found in experiments. An apparent weakness of our standard model is the tendency to produce anti-phase correlations for fast activity from the two areas. Increasing the inter-areal delays in our model produces alternations of in-phase and anti-phase oscillations. The experimentally observed in-phase correlations can most naturally be obtained by the involvement of both fast and slow inter-areal connections; e.g., by two axon populations corresponding to fast-conducting myelinated and slow-conducting unmyelinated axons.
Animals↗
What is signal and what is noise in the brain?
The response of a cortical neuron to a stimulus can show a very large variability when repeatedly stimulated by exactly the same stimulus. This has been quantified in terms of inter-spike-interval (ISI) statistics by several researchers (e.g., [Softky, W., Koch, C., 1993. The highly irregular firing of cortical cells is inconsistent with temporal integration of random EPSPs. J. Neurosci. 13(1), 334-350.]). The common view is that this variability reflects noisy information processing based on redundant representation in large neuron populations. This view has been challenged by the idea that the apparent noise inherent in brain activity that is not strictly related or temporally coupled to the experiment could be functionally significant. In this work we examine the ISI statistics and discuss these views in a recently published model of interacting cortical areas [Knoblauch, A., Palm, G., 2002. Scene segmentation by spike synchronization in reciprocally connected visual areas. I. Local effects of cortical feedback. Biol. Cybernet. 87(3), 151-167.]. From the results of further single neuron simulations we can isolate temporally modulated synaptic input as a main contributor for high ISI variability in our model and possibly in real neurons. In contrast to alternative mechanisms, our model suggests a function of the temporal modulations for short-term binding and segmentation of figures from background. Moreover, we show that temporally modulated inputs lead to ISI statistics which fit better to the neurophysiological data than alternative mechanisms.
Action Potentials↗