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Biomedical subjects

R Beck

Publications and source records attributed to R Beck.

At least 91 records · Page 5Linked to original sources
PubMed1996

[Diagnosis of intraorbital meningioma].

Demonstration of radiological appearance and the differential diagnosis of intraorbital meningeomas in two cases. CT-assisted core needle biopsy offers a reliable and easy-to-perform possibility of minimal invasive diagnosis in tumours which are difficult to classify.

Aged↗
PubMed1995

Vacuum phenomena in insufficiency fractures of the sacrum.

OBJECTIVE: Insufficiency fractures of the sacrum are found in women who have undergone radiation therapy to the lower abdomen as well as those suffering from osteoporosis of postmenopausal, steroid-induced, or primary biliary cirrhosis-related origin. Increased uptake in bone scintigraphy and osteolytic changes in these fractures can be misinterpreted as bone metastases, leading to unnecessary biopsies and other procedures in the ensuing search for non-existent primary tumor. PATIENTS: In eight female patients averaging 69.4 years of age, insufficiency fracture of the sacrum was diagnosed by computed tomography (CT) and bone scintigraphy. Three underwent a total of five MRI examinations. Malignancy was excluded by histology in two patients and follow-up of at least 6 months in the remainder. Retrospective analysis of CT scans of 13 patients with metastases in the sacrum revealed no vacuum phenomena. RESULTS: In seven of eight patients with insufficiency fracture of the sacrum, vacuum phenomena were shown on CT examination. The gas was localized centrally within the ventral part of the fracture in three patients; gas was located in ten adjacent sacro-iliac joints of six patients. CONCLUSIONS: The vacuum phenomenon may be an incidental finding in osteoarthritis of the sacro-iliac joint, but it has not been previously recognized in IFS. The presence of intra-articular vacuum phenomena in the sacro-iliac joints in combination with a sacral fracture and vacuum phenomena located within the sacral fracture supports a diagnosis of insufficiency fracture or may indeed be the clue by which this diagnosis is established.

Aged↗
PubMed1995

[Use of ipratropium bromide by inhalation in the treatment of acute asthma in children. Clinical experience].

Clinical experience. Anticholinergic drugs, notably atropine, have long been known to be potent bronchodilators, but their use was limited by systemic absorption and significant side effects. Ipratropium bromide has no systemic anticholinergic action, but maintains the local anticholinergic action on the tracheobronchial tree. In 1984, we observed that in children with acute asthma, treated aggressively with frequent doses of nebulized beta 2 adrenergics, a significant degree of airway obstruction remained, and did not improve with further doses of beta 2 agonists. We postulated that vagal bronchomotor tone might contribute to this problem and that further improvement could be obtained with the use of ipratropium bromide. Ipratropium was shown to be useful in pediatric asthma in the early 1980s. There appeared to be an age difference in the response to the medication. A dose-response curve for nebulized ipratropium was determined. The optimal dose was found to be > 75 micrograms. Repeated studies and extensive experience demonstrated safety and few side effects. In 1984 we studied the effect of adding ipratropium after one hour of treatment with a regimen of frequent nebulized salbutamol in children with acute asthma. We found a slight but significant further improvement in FEV1, beginning one hour after administration of ipratropium. Further studies confirmed these findings, when using two doses of combined ipratropium/fenoterol an hour apart or every 40 minutes for three doses. One study using ipratropium every eight hours failed to show a change, confirming the need to use the medication more frequently. For the past six years, we have been using a protocol that incorporates ipratropium in the treatment of acute asthma in children. (ABSTRACT TRINCATED AT 250 WORDS)

Acute Disease↗
PubMed1995

Correcting myopic astigmatism with an areal 193 nm excimer laser ablation.

A new system to correct symmetric bow-tie myopic astigmatism with the excimer laser using oval apertures for toric ablations is described. Initial results in two patients who had -5.0 and -5.5 diopters of astigmatism after surgery with six-months follow-up showed a reduction of up to 85% with a minimal axial error of two degrees.

Aged↗
PubMed1995

Monitoring of mixed venous oxygen saturation and pressure from biosensors in the right ventricle. A 24 hour study in patients with heart failure.

Right ventricle venous oxygen saturation was studied in 10 heart failure patients over 24 h using a lead equipped with an oxygen biosensor inserted temporarily. At the same time a pressure sensor, incorporated in the same lead to measure right ventricular pulse pressure and maximum positive and negative rate of pressure development (RV dP/dt), was tested to see whether it would interfere with the oxygen sensor. Data from the biosensor lead were continuously compared with mixed venous oxygen saturation obtained from a fibreoptic Swan-Ganz catheter with the tip in the pulmonary artery. For reference, blood samples were drawn at regular intervals from this catheter. A provocative protocol was used to cause haemodynamic changes. There was good correlation between oxygen saturation in the right ventricle (biosensor-derived) and mixed venous oxygen saturation in the pulmonary artery (fibreoptic-derived) (r = 0.86) and between sensor-obtained right ventricular oxygen saturation and oxygen saturation in the blood samples from the pulmonary artery (r = 0.90). Changes in central haemodynamics were also well reflected by changes in pulse pressure and dP/dt derived from the pressure sensor. As it was not possible to obtain absolute pressures no attempt was made to compare the pressure changes with conventional haemodynamics. These 24 h haemodynamic measurements suggest that a biosensor-equipped lead placed in the right ventricle could be a valuable tool for long-term monitoring of mixed venous oxygen saturation and pressure in patients with congestive heart failure.

Aged↗
PubMed1995

The acoustic properties of snores.

This study was undertaken in an attempt to characterize the acoustic properties of snoring sounds in the time and frequency domains, and to correlate between these properties and the mechanical events underlying their production. Three experimental set-ups were used: 1) Dog model--six mongrel dogs, in which partial upper airway obstruction was created by an implanted supraglottic balloon. Flow, supraglottic pressure, and snoring sounds were recorded during different degrees of obstruction. Fifteen to 20 snores from each dog (total 100 snores) were analysed. 2) Simulated human snores--Six simulated snores from each of four subjects were recorded in two locations (trachea and ambient) with simultaneous airflow, and their correlations examined. 3) Snoring patients--snores were recorded with an ambient microphone from nine subjects with "heavy" snoring and no obstructive sleep apnoea (OSA). Forty to 50 snores from each subject were analysed (total of 400 snores). The snoring sound was analysed in the time (time-expanded waveform) and frequency (power spectrum) domains. After analysing these snores, we were able to identify two dominant patterns which are distinctly different from each other: the "simple-waveform" and the "complex-waveform". The complex-waveform snore is characterized by repetitive, equally-spaced, train of sound structures, starting with a large deflection followed by a decaying amplitude wave. In the frequency domain, it is characterized by multiple, equally-spaced peaks of power (comb-like spectrum). Simple-waveform snores have a quasi-sinusoidal waveform, with a range of variants, and almost no secondary internal oscillations. Their power spectrum contains only 1-3 peaks, of which the first is the most prominent. We developed a mathematical representation of these waveforms, which is presented along with its implications. The complex-waveform snores result from colliding of the airway walls and represent actual brief airway closure. Simple-waveform snores are of higher frequency and probably result from oscillation around a neutral position without actual closure of the lumen.

Acoustics↗
PubMed1995

Inflammatory pseudotumor of the anterior orbit. A symptom in allergic granulomatous angiitis (Churg-Strauss syndrome).

Allergic granulomatosis accompanied by angiitis (Churg-Strauss syndrome) constitutes an unusual disorder which is characterized clinically by bronchial asthma and hypereosinophilia, accompanied by systemic symptoms of histopathologically and by necrotizing vasculitis, extravascular granulomas and tissue infiltration by eosinophils. We report a case of a 4 year-old child presenting with acute pneumonia and deteriorated general condition. The biopsy of an inflammatory pseudotumor of the right anterior orbit revealed necrotizing vasculitis, extravascular epitheloid granuloma and eosinophilic tissue infiltration. These are characteristic changes of allergic granulomatous vasculitis (Churg-Strauss syndrome. Laboratory findings were characterized by blood eosinophilia, increased IgE value and the presence of antineutrophil cytoplasmic ant antibodies (p-ANCA). Local and systemic manifestations quickly regressed after parenteral application of corticosteroids. Two exacerbations of inflammatory pseudotumor occurred after reduction of the corticosteroid dosage. Systemic vasculitic syndromes are rare in childhood. Orbital manifestations in Churg-Strauss syndrome in childhood have never been reported.

Biopsy↗
PubMed1994

Mutation in dipZ leads to reduced production of active human placental alkaline phosphatase in Escherichia coli.

We have tested the expression of alkaline phosphatases in a mutant strain of Escherichia coli deficient in dipZ, a gene coding for a protein involved in cytochrome c biogenesis, and the isogenic wild-type strain. The yield of soluble and active human placental alkaline phosphatase was significantly reduced in the mutant but could be fully recovered by expression of dipZ subcloned in a vector with low copy number. Overexpression of E. coli alkaline phosphatase was unaffected in the mutant with or without dipZ co-expression.

Alkaline Phosphatase↗