Biomedical subjects
G Hertel
Publications and source records attributed to G Hertel.
Aspiration complicating bronchopulmonary dysplasia.
The purpose of this study was to study the relationship of aspiration with ongoing respiratory difficulties in infants with bronchopulmonary dysplasia (BPD). Twelve infants with BPD were identified out of 314 children who had flexible bronchoscopy between 1987 and 1990; 11 of 12 had bronchoalveolar lavage (BAL). The lipid index (LI) was used to quantify the degree of lipid-laden macrophages in the BAL fluid as a marker of aspiration. The age range at the time of bronchoscopy was 3 months to 5 years. The LI was considered positive in 6 of 11 subjects. A pH probe study was done on seven subjects with concordant findings in five. Other findings included dynamic or structural airway abnormalities in 10 of the 12 subjects. These data suggest that aspiration frequently is associated with BPD in addition to the previously recognized dynamic and structural airway problems. The predisposition to gastroesophageal reflux and laryngeal injury probably accounts for the increased aspiration risk in children with BPD.
Clinical use of the heparin nomogram.
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Immunologic relatedness of extracellular ligninases from the actinomycetes Streptomyces viridosporus T7A and Streptomyces badius 252.
Four isoforms of the extracellular lignin peroxidase of the ligninolytic actinomycete Streptomyces viridosporus T7A (ALip-P1, P2, P3, and P4) were individually purified by ultrafiltration and ammonium sulfate precipitation, followed by electro-elution using polyacrylamide gel electrophoresis. Three of the purified peroxidases were compared for their immunologic relatedness by Western blot analysis using a polyclonal antibody preparation produced in rabbits against pure isoform P3. The anti-P3 antibody was also tested for its reactivity towards a lignin peroxidase from the white-rot fungus Phanerochaete chrysosporium and another ligninolytic actinomycete Streptomyces badius 252. Results showed that peroxidases ALip-P1 through ALip-P3 are immunologically related to one another. The peroxidases of S. badius, but not the peroxidase of P. chrysosporium, also reacted with the antibody, thus indicating that the lignin peroxidases of S. viridosporus and S. badius are immunologically related. Based upon its specific affinity, lignin peroxidase isoform ALip-P3 of S. viridosporus was readily purified using an anti-P3 antibody affinity column.
Cloning and expression of a lignin peroxidase gene from Streptomyces viridosporus in Streptomyces lividans.
A lignin peroxidase gene was cloned from Streptomyces viridosporus T7A into Streptomyces lividans TK64 in plasmid pIJ702. BglII-digested genomic DNA (4-10 kb) of S. viridosporus was shotgun-cloned into S. lividans after insertion into the melanin (mel+) gene of pIJ702. Transformants expressing pIJ702 with insert DNA were selected based upon the appearance of thiostrepton resistant (tsrr)/mel-colonies on regeneration medium. Lignin peroxidase-expressing clones were isolated from this population by screening of transformants on a tsr-poly B-411 dye agar medium. In the presence of H2O2 excreted by S. lividans, colonies of lignin peroxidase-expressing clones decolorized the dye. Among 1000 transformants screened, 2 dye-decolorizing clones were found. One, pIJ702/TK64.1 (TK64.1), was further characterized. TK64.1 expressed significant extracellular 2,4-dichlorophenol (2.4-DCP) peroxidase activity (= assay for S. viridosporus lignin peroxidase). Under the cultural conditions employed, plasmidless S. lividans TK64 had a low background level of 2.4-DCP oxidizing activity. TK64.1 excreted an extracellular peroxidase not observed in S. lividans TK64, but similar to S. viridosporus lignin peroxidase ALip-P3, as shown by activity stain assays on nondenaturing polyacrylamide gels. The gene was located on a 4 kb fragment of S. viridosporus genomic DNA. When peroxidase-encoding plasmid, pIJ702.LP, was purified and used to transform three different S. lividans strains (TK64, TK23, TK24), all transformants tested decolorized poly B-411. When grown on lignocellulose in solid state processes, genetically engineered S. lividans TK64.1 degraded the lignocellulose slightly better than did S. lividans TK64. This is the first report of the cloning of a bacterial gene coding for a lignin-degrading enzyme.
[Dysphagia from the neurologic viewpoint].
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[MRT in primary and tumor-induced syringomyelia].
The MRI findings in 26 patients with primary syringomyelia and eight patients with a syrinx due to an intramedullary tumour were studied retrospectively. In general, the syrinx in the tumour cases resembled the appearance of primary syringomyelia. However, a specific and sensitive sign of tumour-induced syringomyelia was irregularity of the spinal cord close to the tumour (eight cases of eight), eccentric position of the lumen (seven of eight), and a diffuse increase of signal intensity on T2-weighted images (eight of eight). Primary syringomyelia also showed increased signal intensity on T2-weighted images outside the lumen, but this was closely related to the cavity. The use of Gd-DTPA improved demarcation of the tumour from the syrinx in all cases. Widening of the spinal canal and ectopia of cerebellar tonsils was a typical finding in primary syringomyelia. MRI proved a reliable method for distinguishing between a tumour-induced syrinx and primary syringomyelia.
[Anesthesia-induced changes in the preload-dependent circulatory reactions in patients with coronary heart disease].
The influence of preload changes (table tilt) on the hemodynamic regulation before and after induction of neuroleptanalgesia was studied in 31 patients with coronary heart disease. The induced preload changes are balanced in the awake patient for the maintenance of normal arterial pressure by regulation of stroke volume and peripheral vascular resistance. This regulation does not exist after induction of anaesthesia. Splitting the patients into sub-groups with good or poor left ventricular function, different ventricular function curves were obtained before and after the induction of anaesthesia. The pharmacologic and ventilatory reasons for the changed regulation of circulation are discussed. For investigations into hemodynamic changes produced by intervention in anaesthesia and intensive therapy, it is recommended to define more exactly the cardiovascular status of patients and the study conditions.
Multiple sclerosis: diagnostic value of computerized tomography with delayed scanning after a double-dose of contrast medium in comparison with other diagnostic tests.
In 63 cases of clinical definite or suspected MS we compared the results of CSF analysis, VEP, BAEP, CT scanning without and after double dose contrast, in 17 cases also those of MRT. We found that CSF analysis had the highest rate of abnormal findings, followed by MRT. VEP and CT with double dose contrast showed similar sensitivity, while BAEP and CT without contrast had disappointing results. We think that CT with delayed scanning after double dose contrast can be a very useful investigation in early and doubtful cases of MS, until MRT will become a more widespread and less expensive investigation.
Characterization of an extracellular lignin peroxidase of the lignocellulolytic actinomycete Streptomyces viridosporus.
Previously we reported production of an extracellular lignin-inducible peroxidase by Streptomyces viridosporus (M. Ramachandra, D.L. Crawford, and A.L. Pometto III, Appl. Environ. Microbiol. 53:2754-2760, 1987). This peroxidase was shown to oxidize 3,4-dihydroxyphenylalanine, 2,4-dichlorophenol, homoprotocatechuic acid, caffeic acid, and N,N,N',N'-tetramethylphenylenediamine and was found in higher than normal levels in strains enhanced for lignocellulose degradation. In the present study, we used a pure extracellular enzyme preparation with high peroxidase isoform P3 activity to oxidize lignin substructure model compounds of both the 1,2-diaryl propane and arylglycerol-beta-aryl ether types and containing C alpha-carbonyl and C alpha-hydroxyl groups. The reactions were monitored by gas chromatography-mass spectrometry and high-pressure liquid chromatography techniques. In the presence, but not the absence, of hydrogen peroxide, the enzyme preparation catalyzed C alpha-C beta bond cleavage in the side chains of the diaryl ethers 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)propane-1,3-diol (I) and 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)propan-1-one (II) and the diaryl ethane 1-(4-methoxyphenyl)-2-(phenyl)ethan-1-one (III). Rapid hydrogen peroxide consumption was observed when the enzyme preparation was added to either milled corn lignin or lignocellulose. Additional characterizations showed that this enzyme is a heme protein (Soret band, 408 nm) and a major component of the ligninolytic system of S. viridosporus T7A. This is the first report of a lignin peroxidase in a bacterium. We have designated this new lignin peroxidase as ALiP-P3.
Double-blind crossover study comparing sodium cromoglycate, reproterol, reproterol plus sodium cromoglycate, and placebo in exercise-induced asthma.
Sixteen patients were included in the analysis of this double-blind crossover study comparing the effect of sodium cromoglycate, reproterol, sodium cromoglycate plus reproterol, and placebo in exercise-induced asthma. Both the sodium cromoglycate and the reproterol-containing treatment significantly inhibited exercise-induced asthma. The best protection is effected by the combination of sodium cromoglycate and reproterol. A synergistic effect of both medications could not be confirmed statistically so that their combined effect is simply additive.
[Neurologic symptoms in Legionella infection. A case report of the clinical aspects and diagnosis of legionellosis].
In patients with infection from Legionella pneumophila, it must be taken into consideration that the nervous system may be involved. This involvement can precede the pneumonia by several days. Headache, acute mental status changes and cerebellar dysfunctions are the most common neurological symptoms. In the case reported, extrapyramidal disturbances were also observed that are rarely found in association with Legionella infection. There are grounds for the assumption that Legionella toxins cause impairment to the nervous system. The neurological symptoms are not specific enough to allow differentiation of this infection from pneumonia of other etiologies.
[Magnetic resonance tomography in syringomyelia].
Thirteen patients with a clinical diagnosis of syringomyelia were examined by nuclear tomography (0.35 T magnet) in the spin-echo mode. In all thirteen patients, the T1 images (SE 400/35) showed a longitudinal cavity with a signal intensity of CSF. The shape and extent of the syrinx could be adequately demonstrated in 12 of the 13 examinations. Downward displacement of the cerebellar tonsils was seen in eight cases. The examination took between half and one hour. Advantages of magnetic resonance tomography (nuclear tomography) include the absence of artifacts, images in the line of the lesion and its non-invasiveness.
Effect of immunosuppressive drugs (azathioprine).
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Quantitative electron microscopy of sensitized rat mast cells.
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[Treatment of myasthenia gravis with plasmapheresis (author's transl)].
Nine out of eleven severely ill patients with myasthenia gravis could be markedly improved by a combination of immunosuppressive drug therapy and plasmapheresis, two patients however suffered grave complications. The effectiveness of plasma exchange underlines the importance of plasma factors in the pathomechanism of myasthenic functional disturbance. Treatment with plasmapheresis may be regarded as a supportive measure of immunosuppressive drug therapy. However, the considerable risk and high technical requirements limit the indication to severe forms of the disease.
Influence of temperature on isometric contraction and passive muscular tension in paramyotonia congenita (Eulenburg).
Four patients without symptoms of episodic hyperkalemic weakness from two families with paramyotonia congenita (Eulenburg) are described. 1. Maximum voluntary muscle contraction of the upper and lower arm was studied under isometric conditions at different temperatures. If the temperature was lowered stepwise, distinct paresis occured at 32--31 degrees C which increased with the amount of muscular effort. The upper arm muscles, however, developed weakness gradually after cooling. 2. During cooling of the resting muscle, the EMG showed dense spontaneous activity of the fibrillary type, which decreased again at about 30 degrees C. It can be assumed that in paramyotonia congenita cooling produces muscle cell membrane depolarization which at a critical level causes the firing of action potentials and finally muscular paresis. 3. Increasing muscular stiffness can be interpreted as abnormally slow muscular relaxation after isometric contraction. In the forearm muscles the time to 3/4 relaxation after cooling was about six times normal, in the upper arm muscles only two times normal. As an additional parameter the mechanical resistance to passive stretching of a muscle has been studied. This passive muscular tension increased simultaneously with the onset of weakness. 4. The close relation between weakness and stiffness suggest that both symptoms are caused by the same basic defect which is probably located in the sarcolemma. It is suggested that a defect of the sodium channel causes a cooling-dependent increase in sodium conductance. Raised intracellular sodium causes in the first place membrane depolarization, and in the second place depression of calcium reuptake through competition by sodium for calcium binding sites. This would explain muscle stiffness and delayed relaxation as well.
[Treatment of obese female patients with fenproporex within the framework of gynecologic practice].
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