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Biomedical subjects

M Reuter

Publications and source records attributed to M Reuter.

At least 127 records · Page 7Linked to original sources
PubMed1997

Computed tomography of the chest in diving-related pulmonary barotrauma.

Arterial gas embolism due to barotrauma of the lungs is a severe complication in compressed air diving. Precipitating factors are often missed on plain chest radiology. This study was conducted to detect occult lung disease predisposing to the development of pulmonary barotrauma in conditions associated with a change in ambient pressure. During the past 4 years, 11 patients who have suffered pulmonary barotrauma with or without subsequent development of cerebral or spinal arterial gas embolism underwent computed tomography of the chest several days post-injury. Examinations were conducted either using the conventional technique (n = 7) or, more recently, in the spiral mode (n = 4). Chest radiographs were available in all cases. In five patients CT revealed subpleural emphysematous blebs or cysts that were not detected by conventional radiography. Follow-up studies performed in two of these cases several months post-injury showed that the cystic lesions did not resolve. We assume that the lung cysts or blebs are preexisting conditions which caused pulmonary barotrauma. Computed tomography of the chest, preferably in the spiral mode, is recommended in any case of suspected pulmonary barotrauma in order to evaluate the possibility of pre-existing pathology and to predict future fitness to dive.

Adult↗
PubMed1997

Risk factors for pulmonary barotrauma in divers.

STUDY OBJECTIVES: Pulmonary barotrauma (PBT) of ascent is a feared complication in compressed air diving. Although certain respiratory conditions are thought to increase the risk of suffering PBT and thus should preclude diving, in most cases of PBT, risk factors are described as not being present. The purpose of our study was to evaluate factors that possibly cause PBT. DESIGN: We analyzed 15 consecutive cases of PBT with respect to dive factors, clinical and radiologic features, and lung function. They were compared with 15 cases of decompression sickness without PBT, which appeared in the same period. RESULTS: Clinical features of PBT were arterial gas embolism (n=13), mediastinal emphysema (n=1), and pneumothorax (n=1). CT of the chest (performed in 12 cases) revealed subpleural emphysematous blebs in 5 cases that were not detected in preinjury and postinjury chest radiographs. A comparison of predive lung function between groups showed significantly lower midexpiratory flow rates at 50% and 25% of vital capacity in PBT patients (p<0.05 and p<0.02, respectively). CONCLUSIONS: These results indicate that divers with preexisting small lung cysts and/or end-expiratory flow limitation may be at risk of PBT.

Adult↗
PubMed1997

Management of involuntary childlessness.

Any definition of involuntary childlessness has to consider the difference between sterility and subfertility. As the latter affects about 20-30% of all couples at least once in their lives, general practitioners (GPs) may be the first to be confronted with this problem. This review presents the most relevant diagnostic and therapeutic options in cases of female or male infertility, and discusses the new assisted reproductive technologies (such as insemination, in vitro fertilization, gamete transfer and intracytoplasmatic sperm injection) so that GPs may adequately inform their patients about these procedures and their risks and outcomes. Although controversial, involuntary childlessness and its clinical treatment seem to have a strong psychological impact on a couple's social, emotional and sexual life. Being available for discussion with childless couples and offering ongoing support may be the most important role for the GP in this context.

Family Practice↗
PubMed1997

[Evaluation of the validity of spiroergometric parameters in the differentiation of circulatory and ventilatory physical limitation].

BACKGROUND: One of the indications postulated for cardiopulmonary exercise testing (CPX) is the distinction between ventilatory and cardiocirculatory reasons of an exercise limitation. Though data such as anaerobic threshold, breathing- and heart-rate-reserve, difference of arterial and alveolar oxygen pressure, ratio of ventilation to O2 and CO2 output and aerobic capacity are commonly considered in CPX interpretation, exact choice of parameters and cut-off-points is not definitely clear. The aim of our study therefore was to scrutinize the validity of these parameters and the recommended cut-off-points. A second goal was to evaluate the reliability of a standardized CPX interpretation as postulated by Wassermann and Palange. PATIENTS AND METHODS: We examined 19 patients with congestive or ischemic cardiomyopathy, 24 subjects with chronic obstructive or interstitial lung disease (n = 11 resp. n = 13). The control group consisted of 15 healthy people. During incremental cycle exercise we measured the ventilatory frequency, the peak O2 uptake and the oxygen pulse as well as the above mentioned parameters. Data were interpreted according to Wassermann and Palange in order to confirm the diagnosis of a cardiocirculatory or ventilatory conditioned exercise limitation. Additionally we determined the cut-off-points with the highest diagnostic value for our patient groups. RESULTS: According to Palange only 7% of the diagnosis could be confirmed, 55% were correctly ascertained by data interpretation according to Wassermann. Breathing reserve (45% of maximum voluntary ventilation) proved to be the only parameter with satisfying selectivity (sensitivity = 75%; specificity = 95%). Diagnostic value of all other recorded data was worse by far. CONCLUSIONS: Our study shows that standardized interpretation of CPX data does not lead to the correct diagnosis in a satisfying percentage. In any case results have to be confirmed by conventional tests such as ECG or spirometry, so that the additional diagnostic value of CPX in patients with an exercise limitation of unknown origin has to be seen very critically. Except breathing reserve from our point of view there is still no valid parameter or cut-off-point to distinct cardiocirculatory from ventilatory exercise limitation that can be recommended.

Adult↗
PubMed1997

[Striatal uptake of I-123-beta-CIT and I-123-IBZM in patients with extrapyramidal symptoms].

AIM: This pilot study deals with the question whether characteristic changes in local cerebral dopamine transporter function and D2-receptor binding capacity can be shown with SPET in idiopathic Parkinson syndrome (IPS) and secondary Parkinson syndrome (SPS). METHODS: In 16 patients (6 with IPS, 6 with SPS except Wilson's disease, and 4 with Wilson's disease) SPET studies were performed using I-123-beta-CIT and I-123-IBZM and a dual-head gamma camera. Images were obtained 20-24 h and 2 h post injection, respectively. For semiquantitative analysis count density ratios of basal ganglia (BG) and cerebellum (CER) were determined for I-123-beta-CIT and ratios between BG and medial frontal cortex (MFC) for I-123-IBZM. RESULTS: The BG/CER ratio in the I-123-beta-CIT studies averaged 3.04 +/- 0.83 in IPS and 7.73 +/- 3.28 in SPS (p < 0.01) (except Wilson's disease). In patients with IPS, the BG/MFC I-123-IBZM ratios of basal ganglia contralateral to the symptomatic side exceeded that of the individual ipsilateral BGs (1.75 +/- 0.12 vs. 1.61 +/- 0.16); these ratios were significantly reduced when compared with those of SPS patients, although the differences were less pronounced than those of I-123-beta-CIT uptake values. In some of the patients with Wilson's disease the BG/MFC ratio for I-123-IBZM was dramatically reduced (as low as 1.29), whereas I-123-beta-CIT uptake was only slightly reduced when compared with that of SPS patients (8.00 +/- 2.90, p < 0.01). CONCLUSION: It is concluded that the neurochemical changes that can be anticipated in the above diseases can be monitored with SPET. I-123-beta-CIT, however, appears to be more adequate to differentiate IPS from SPS than I-123-IBZM.

Adult↗
PubMed1996

Trauma of the chest.

Trauma to the chest may cause a wide range of injuries including fractures of the thoracic skeleton, contusion or laceration of pulmonary parenchyma, damage to the tracheobronchial tree, diaphragmatic rupture or cardiac contusion. Conditions affecting primarily extrathoracic sites may have indirect effects on the lungs causing adult respiratory distress syndrome or fat embolism. Laceration of the aorta is the typical and likewise most life threatening complication of massive blunt chest trauma necessitating immediate diagnosis and repair. Conventional radiography rather than cross-sectional imaging is the mainstay in diagnosing thoracic trauma. During the critical phase with often concomitant shock, pelvic and spinal injuries tailored radiographic views or even upright chest radiographs are impractical. The severely traumatized patient is usually radiographed in the supine position and suboptimal roentgenograms may have to be accepted for several reasons. It is well documented that many abnormalities detected on CT were not apparent on conventional radiographs, but CT is reserved for hemodynamical stable patients. Nevertheless certain situations like aortic rupture require further evaluation by CT and aortography. The value of conventional radiography, CT, MRI and aortography in chest trauma is reviewed and typical radiographic findings are presented.

Adult↗
PubMed1996

Influence of different fasting periods on P-31-MR-spectroscopy of the liver in normals and patients with liver metastases.

The purpose of this study was to determine the influence of different fasting periods on the in vivo P-31-MR spectroscopy of the healthy liver and patients with liver metastases. Image-guided localized P-31-MRS was performed in 24 patients with liver metastases and in 20 healthy volunteers. The spectra were obtained with a whole body scanner operating at 1.5 T using a surface coil. The P-31-MRS was performed after a fasting period of 3-5 h (group 1) and after overnight fasting (group 2). The PME/beta-NTP, PDE/beta-NTP and Pi/beta-NTP were calculated from P-31-MR spectra and were compared in relation to the nutrition status of the volunteers and patients. The PME/beta-NTP and PDE/beta-NTP were significantly increased in spectra of patients with metastases. There were no significant changes in the ratios of phosphorus metabolites in healthy liver tissue or in liver metastases after a fasting period of 3-5 h as compared with overnight fasting.

Adult↗
PubMed1996

Neuronal signal substances in asexual multiplication and development in flatworms.

1. The phenomenon of asexual multiplication is rare in the animal kingdom. It occurs, however, in all main flatworm taxa. Flatworms are characterized by an extensive versatility, ranging from the different types of asexual multiplication to the different orthogonal plans for the nervous system. The role of the nervous system in the asexual multiplication taking place in flatworms is pointed out and discussed. 2. Immunocytochemical studies of the changes in the flatworm neuroanatomy show that the nervous system, particularly the main never cords, has a central role during asexual development. 3. Antibodies to different neuronal substances yield different immunoreactivity patterns and develop according to different time schedules. Serotoninergic nervous elements seem to have a leading role. 4. Substances produced by the nervous system influence fissioning and subsequent regeneration in free-living flatworms in the following ways. (a) A function as a wound hormone has been suggested for the neuropeptide RF-amide. (b) Mitogenic effects have been shown for several biogenic amines and neuropeptides. (c) Inhibitory roles are suggested for somatostatin and melatonin in connection with cell proliferation respective fissioning. 5. Growth factors have been observed both in free-living and parasitic flatworms. 6. Cells reactive to antibodies against epidermal growth factor increase in number in parallel with increases in mitotic activity in the gull tapeworm and occur in regions with high mitotic activity. A correlation between these two phenomena is suggested.

Animals↗
PubMed1996

NO nerves in a tapeworm. NADPH-diaphorase histochemistry in adult Hymenolepis diminuta.

The free radical nitric oxide (NO), which is synthesized by nitric oxide synthase (NOS), has recently been discovered to function as a neuronal messenger. The presence of NOS was detected in the nervous system of adult Hymenolepis diminuta with NADPH-diaphorase (NADPH-d) histochemistry. The NADPH-d histochemical reaction is regarded as a selective marker for NOS in neuronal tissue. NADPH-d staining was observed in nerve fibres in the main and minor nerve cords and the transverse ring commissures, and in cell bodies in the brain commissure, along the main nerve cords, in the suckers and the rostellar sac. NADPH-d staining was also observed in the wall of the internal seminal vesicle and the genital atrium. The pattern of NADPH-d staining was compared with that of the 5-HT immunoreactive nervous elements. The NADPH-d staining reaction and the 5-HT immunoreactivity occur in separate sets of neurons. This is the first time the NADPH-d reaction has been demonstrated in the nervous system of a flatworm, indicating that NOS is present and that NO can be produced at this level of evolution.

Animals↗
PubMed1996

[Preoperative differential diagnosis of cystic adnexal tumors: double-contrast MRT].

PURPOSE: Preoperative assessment of adnexal lesions as benign or malignant by MRI with gastrointestinal and intravenous contrast. METHODS: 46 patients with benign (n = 42) and malignant (n = 4) cystic adnexal tumours underwent MRI of the pelvis. Transaxial and coronal images were acquired using conventional T1- and T2-weighted SE-sequences after oral administration of superparamagnetic iron oxide particles (Ferristene). Additional T1-weighted SE-images were obtained immediately following gadodiamide (Gd DTPA-BMA) injection. RESULTS: MRI correctly classified the four malignant lesions, whereas nine histologically benign lesions were misdiagnosed as malignant. Intravenous contrast yielded a superior delineation of intratumor architecture. CONCLUSION: Due to exclusion of solid structures. MRI with oral and i.v. contrast enables to dismiss suspected malignity in cystic adnexal lesions. Because of the non-specificity of the macroscopic criteria of dignity, the MR diagnosis "malignity" is of limited value.

Adenocarcinoma↗
PubMed1996

Pulmonary barotrauma of a diver using an oxygen rebreathing diving apparatus.

A 22-yr-old healthy male diver performed a dive using a closed circuit oxygen rebreathing apparatus according to normal procedure. After the dive he developed clinical symptoms of mediastinal emphysema. A chest X-ray taken 1 d after the dive showed a discrete "tram track" sign in the left paracardial region. Spiral volumetric computed tomography of the chest 4 d postinjury detected a small subpleural emphysematous bulla next to the left ventricle, the pneumomediastinum being absorbed in the meantime. Clinical outcome of pulmonary decompression barotrauma in the case of oxygen rebreathing may be different from that in compressed air diving, due to the altered gas physics. The necessity for computed tomography of the chest is emphasized, preferably using the spiral mode, in any case of suspected pulmonary barotrauma.

Adult↗
PubMed1996

[Diving-associated pulmonary barotrauma as a rare differential diagnosis in internal medicine-pneumologic ambulatory care].

Arterial gas embolism due to pulmonary barotrauma (PBT) is a well known fatal complication in compressed air diving. Pulmonary damage is often missed in conventional diagnostic radiology. We present two cases of PBT in recreational divers, in which pre and post accidental chest x-rays were negative but chest-CT showed peripheral bullae in the lower lung lobes preferably responsible for PBT, Chest-CT is recommended in any case of suspected PBT to evaluate the possibility of preexisting pathology in order to predict further diving fitness.

Adult↗
PubMed1995

Restriction endonucleases functionally interacting with two DNA sites.

Simultaneous interaction with two recognition sites was found to be a precondition for DNA cleavage by certain type-II and type-III restriction endonucleases. Nevertheless, the molecular mechanisms of the protein-DNA interaction are different between members of both classes of enzymes.

Binding Sites↗
PubMed1995

Overproduction of His-tagged EcoRII restriction endonuclease and terminally deleted mutant proteins.

EcoRII was the first restriction endonuclease (ENase) reported requiring the cooperative interaction with at least two DNA sites for activity. Using two different expression systems the enzyme could be purified and its special substrate requirements were further analyzed. At the present state of knowledge we suggest a model of simultaneous binding of two DNA sites to one dimeric enzyme molecule (see Krüger et al., FEMS Microbiol. Rev. (1995) in press).

Binding Sites↗
PubMed1995

Hyperexpressed EcoRII renatured from inclusion bodies and native enzyme both exhibit essential cooperativity with two DNA sites.

EcoRII was the first restriction endonuclease (ENase) reported needing the cooperative interaction with at least two DNA sites for activity. We constructed an EcoRII-overproducing strain of Escherichia coli by placing the coding sequence under control of the T7 gene 10 regulatory elements. The yield of EcoRII expression could be increased to about 10% of total soluble cellular protein. Inclusion bodies are formed that mainly consist of insoluble EcoRII molecules. After solubilization by 6 M guanidine hydrochloride refolding of the enzyme was achieved by dilution into appropriate buffer. The endonuclease was purified to homogeneity from both the soluble protein fraction and the protein renatured from inclusion bodies. Their identity was proven by circular dichroism and analysis of enzyme activity with respect to the special substrate requirements of EcoRII. It is shown that EcoRII cleavage of oligodeoxyribonucleotide duplexes (oligo duplexes) with only one recognition site follows a sigmoidal concentration dependence, i.e., they cannot be cleaved below a distinct low DNA concentration where simultaneous interaction with two substrate molecules is no longer possible. We demonstrate that the restriction of oligo duplexes containing two recognition sites does not show this concentration dependence, confirming an intramolecular site cooperativity.

Base Sequence↗