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Biomedical subjects

F Riedel

Publications and source records attributed to F Riedel.

At least 55 records · Page 3Linked to original sources
PubMed1999

Argon plasma coagulation for the treatment of hereditary hemorrhagic telangiectasia.

OBJECTIVES: Patients with (HHT) often suffer from recurrent epistaxis, which poses considerable therapeutic problems. Theoretical considerations render argon plasma coagulation (APC) a promising new therapeutic approach. STUDY DESIGN: In a prospective study 12 patients (aged 8-68 y) who presented with a long history of treatment for epistaxis were treated with telangiectasia in the nasal mucosa. After 2 weeks and again after 4 months the treatment results were evaluated by questionnaire. METHODS: APC is based on high-frequency electric energy transmitted through ionized argon gas to the tissue in a noncontact mode. Coagulation and desiccation of tissue are limited to 1 to 2 mm of penetration and therefore risk of tissue damage is low. Coagulative effects are best in tissue with high electrical conductivity, especially blood vessels. RESULTS: All patients were satisfied with the postoperative results. Frequency and intensity of bleeding were significantly reduced. All patients reported better postoperative results than with any other treatment they had received previously. CONCLUSION: First clinical experience shows that APC is a useful alternative for the treatment of telangiectasia in the nasal mucosa and should be a therapeutic option for this disease.

Adolescent↗
PubMed1998

[Argon plasma coagulation in treatment of hereditary hemorrhagic telangiectasia of the nasal mucosa].

Patients with hereditary hemorrhagic telangiectasia (M. Osler-Rendu-Weber disease) often suffer from recurrent epistaxis that poses considerable therapeutic problems. Dermoplasty, electrocoagulation, laser coagulation, iridium brachytherapy and systemic administration of estrogens have been proposed for treatment. Until recently argon plasma coagulation (APC) was not used in ENT surgery, but theoretical considerations render APC a promising therapeutic method for controlling nasal bleeding. Coagulation of tissue is limited to 1-2 mm of penetration and therefore risk of damage to adjacent tissue is low. Effects are best in tissues with high electric conductivity, especially for coagulating bleeding lesions and blood vessels. We have now treated four patients with telangiectasias in the nasal mucosa who had long histories of treatment for epistaxis. The patients were satisfied with the postoperative results and the frequency and intensity of bleeding were significantly reduced. Initial clinical experiences show that APC is a useful alternative for the treatment of bleeding telangiectasias in the nasal mucosa.

Adult↗
PubMed1998

[Treatment of peri-ocular skin lesions with the erbium:YAG laser].

INTRODUCTION: A great number of consmetically disturbing, cutaneous lesions are localized in the periocular region. While various approaches for treatment such as excision, electrocauterization or cryosurgery often show unsatisfactory results, the use of laser technology is of increasing interest. MATERIAL AND METHODS: A total of 104 patients with different cutaneous periorbital lesions (wrinkles, xanthelasma, syringoma) were treated with a new erbium: YAG laser system (wavelength 2940 nm, pulse duration 0.350 ms and pulse energy 0.1-1.7 Joules), which works on the principle of vaporization. RESULTS: The erbium: YAG laser allows athermic ablation of very thin skin layers without scarring and with minimal lateral thermal injury due an extremely short pulse duration. Periorbital lesions can be treated effectively by erbium: YAG laser, and good to excellent cosmetic results can be obtained. CONCLUSIONS: The use of pulsed erbium: YAG laser is an effective and promising new method for treatment of different superficial periorbital cutaneous lesions.

Adult↗
PubMed1998

Role of sialoglycan structures for the function of the epidermal growth factor receptor and the in vitro proliferation of head and neck cancer.

Squamous cell carcinomas of the head and neck have been found to show a high expression of the receptor for epidermal growth factor (EGF). This overexpression of the receptor has been associated with malignant transformation of cells, although there is still debate as to what extent this receptor takes part in the proliferation of malignant cells and which function it fulfills. The factors which determine receptor-ligand interaction are also not clearly defined. That the extracellular domain of the EGF receptor carries carbohydrate or sialoglycan structures might be important for function of the receptor. Since tumor specific enzymes can possibly alter such structures, it was the aim of our study to investigate the role of these structures on the EGF receptor during the proliferation of head and neck carcinomas. We used the human laryngeal squamous carcinoma cell line HLaC 79 and altered, for the first time, specific glycan structures with sialidase alpha-2,3 and alpha-2,6, causing desialylation. Changes were also produced by endo-beta-galactosidase and sialyltransferase. Findings were monitored by labeling with bromo-deoxyuridine. To determine receptor affinity, 125I-labeled EGF was employed. Results showed that both cell proliferation and receptor affinity depended on the level of sialylation of the receptor carbohydrate side chains. Desialylation led to a statistically significant reduction of tumor cell proliferation to 65 +/- 33% (P < 0.01), while receptor affinity decreased to 70 +/- 26% (P < 0.01). The importance of EGF receptor for the proliferation of malignant cells seems to depend on the level of sialylation of glycan structures on receptor protein. A release of enzymes by tumor cells may then produce auto-control of tumor proliferation on its own.

Binding Sites↗
PubMed1997

[The treatment of juvenile laryngeal papillomatosis with argon plasma coagulation].

HISTORY AND CLINICAL FINDINGS: At 3 years of age a girl known for one year to have progressive juvenile laryngeal papillomatosis with involvement of the lower respiratory tract was seen by her general practitioner because of increasing hoarseness. As about 20 sessions of CO2-laser treatment and adjuvant administration of interferon-alpha had failed to prevent increasing glottal stenosis and spread of the tracheal involvement, a tracheostomy had to be performed. Removal of the papilloma became progressively more difficult and at the age of 6 years she was admitted for further treatment. INVESTIGATIONS: She had marked inspiratory and expiratory stridor. Results of laboratory tests were unremarkable. Examination of the respiratory tract with a flexible endoscope revealed obstruction of the tracheal lumen by the papilloma. TREATMENT AND COURSE: The papilloma was removed by argon plasma coagulation (APC) under general anaesthesia during intermittent apnoeic phases. After four treatment sessions no papilloma could be seen endoscopically. There were no side effects or complications. The interval between treatments has become progressively longer. Further removal of papilloma is only rarely necessary nowadays. CONCLUSION: APC via a flexible endoscope is a promising method in the treatment of juvenile laryngeal papillomatosis involving the lower respiratory tract. It achieves precise, circumscribed tissue penetration without carbonisation or steaming-up, while bleeding can be controlled.

Child, Preschool↗
PubMed1997

A new histobiochemical method to analyze sialylation on cell-surface glycoproteins of head and neck squamous-cell carcinomas.

Oncogenic transformation is often accompanied by alterations of glycosylation on a tumor cell's surface, which may contribute to uncontrolled cell growth. The sialoglycans and degree of sialylation on the cell surface are of increasing interest because of their possible role in metastasis and tissue invasion. Since primary tumors and metastases may differ in the degree of sialylation, we examined the expression of sialic acid as a terminal constituent of lactosaminyl glycans on the cell surfaces of 30 cervical lymph-node metastases and 30 squamous-cell carcinomas of the oropharynx and oral cavity. Cell-surface sialylation was determined by a new histobiochemical assay on cryostat sections and was based on the enzymatic introduction of a fluorescence-labelled sialic acid into lactosaminyl type (Gal-beta 1-4 GlcNAc) oligosaccharide chains of cell-surface-expressed glycoproteins. To this end, tissues were incubated in the presence of 5-acetamido-9-deoxy-9-fluoresceinyl-thioureido neuraminic acid (CMP-9-fluoresceinyl-NeuAc) and alpha-2,6-sialyltransferase. In order to compare the degree of sialylation with the potential total amount of sialylation sites, pretreatment with sialidase for desialylation was required. We observed a significantly higher amount of lactosaminyl-type binding sites for sialic acid on metastases compared to the primary tumors (P = 0.001), indicating a lower degree of sialylation in metastases. In primary tumors no correlation was seen between the amount of binding sites and tumor localization, TNM stage or histologic grading. Pretreatment of specimens with sialidase demonstrated a significant degree of sialylation on both primary tumors and lymph-node metastases, but no difference between primary tumors and metastases. When tumor stroma of primary tumors and metastases was compared, tumor cells showed a higher degree of free binding sites for sialic acid, but a low degree of sialylation. Our results suggest that differences in the degree of sialylation of glycoconjugates on a tumor cell's surface may play an important role in the process of cell metastasis. Our histobiochemical method turned out to be very reliable, effective and readily performed.

Binding Sites↗
PubMed1997

Hexamethylene diisocyanate induction of transient airway hyperresponsiveness in guinea pigs.

The induction of lung injury and the development of airway hyperresponsiveness (AHR) by exposure to hexamethylene diisocyanate (HDI) were studied in a guinea pig model of occupational lung diseases. In addition to an unexposed control group of 16 guinea pigs (A), two groups (B, C) of 8 animals inhaled HDI atmospheres in the range of the threshold limit value (TLV) of 10 ppb for 6 h/day on 5 days/week over a period of 8 weeks. Airway responses to aerosols of 0.125, 0.25, 0.5, 1.0 and 2.0% acetylcholine (ACH) were measured in exposed as well as in unexposed animals. Basal values of respiratory mechanical and cardiovascular parameters were not significantly altered after 8 weeks of HDI inhalation (group B). Furthermore, additional acute challenge by 10 ppb HDI for a period of 60 min, performed under continuous registration of respiratory and cardiovascular parameters, did not cause any significant changes in functional parameters. After 8 weeks of HDI exposure, the amplitude of airway constriction as a response to 2.0% ACH, indicated by the changes in dynamic elastance (Edyn) rose significantly to almost 5 times the ACH response in group A(p < 0.0005). In group C of 8 guinea pigs, ACH response was evaluated after a latency period of 8 weeks. In this group, changes of airway responsiveness to ACH were significantly smaller than in group B without a latency period. They were comparable to those of group A. In summary, HDI-induced airway hyperresponsiveness to ACH in the guinea pig is reversible within 8 weeks of HDI avoidance. It is assumed that the augmented airway responsiveness indicates an increased risk of developing isocyanate-induced obstructive lung diseases.

Acetylcholine↗
PubMed1997

Role of sensory neuropeptides in PIV-3-infection-induced airway hyperresponsiveness in guinea pigs.

Viral respiratory tract infections are known to induce transient airway hyper-responsiveness. The role of the nonadrenergic noncholinergic neuropeptide system on virus-induced airway hyperresponsiveness was studied in the guinea pig. Ten guinea pigs were inoculated with parainfluenza 3 virus (PIV-3.2 x 10(6) PFU) by nasal route. 16 animals served as untreated controls. Viral infection was proven by histological changes and by demonstration of viral antigen using immunohistochemical techniques. Four days after inoculation, airway responsiveness to inhaled acetylcholine (ACH) aerosol was measured in anesthetized and tracheotomized guinea pigs. The ACH concentration which produced an increase of 100% in pulmonary resistance (PC100 RI) and in dynamic elastance (PC100 Edyn) was calculated from a 5-step ACH dose-response curve (0.125, 0.25, 0.5, 1.0 and 2.0% ACH). Two further groups of 8 PIV-3-infected guinea pigs and 8 noninfected control animals were pretreated with capsaicin in increasing doses (50, 100, 125 and 150 mg/kg) on 4 consecutive days starting 6 days before virus inoculation. Measurements of airway responsiveness to ACH were performed 4 days after virus inoculation. Another 5 uninfected control animals were pretreated only with the solvent for capsaicin and inoculated with virus-free cell supermatant. PIV-3 infection increased airway responsiveness to ACH compared to noninfected controls [PC100 RI 0.81 vs. > 2.0% ACH (median). p < 0.002 PC100 Edyn 0.52 vs. 1.07% ACH (median), p < 0.01]. In capsaicin-pretreated PIV-3-infected animals, airway hyperresponsiveness was completely prevented compared to the virus-infected group without capsaicin pretreatment (PC100 RI > 2.0 vs. 0.81% ACH, p < 0.01; PC100 Edyn 1.42 vs. 0.52% ACH p < 0.01). As neuropeptide depletion with capsaicin completely prevented the increase in airway constrictory response to ACH following virus infection, we conclude that neuropeptides are effectively involved in PIV-3-induced airway hyperresponsiveness in the guinea pig.

Acetylcholine↗
PubMed1997

Persistence of airway hyperresponsiveness and viral antigen following respiratory syncytial virus bronchiolitis in young guinea-pigs.

Respiratory syncytial virus (RSV) bronchiolitis in infancy is known to be followed by chronic respiratory symptoms and airway hyperresponsiveness in a subgroup of patients. To further investigate the pathogenesis of RSV-induced chronic airway pathology, we infected young guinea-pigs at 4 weeks of age with RSV applied as an aerosol (n=30), and control guinea-pigs with virus-free culture medium (n=24). Infection was confirmed by positive antibody titre to RSV after 6 weeks, and by typical pathological changes of bronchiolitis after 1 week in six animals from each group. Airway hyperresponsiveness was measured weekly for 5 weeks by histamine challenge, using body-plethysmographic measurement of compressed air (CA). The provocative concentration of histamine producing significant airway obstruction (i.e. CA = 0.1 mL) (PC0.1 mL CA in mg x mL(-1)) was calculated from dose-response curves. Six weeks postinfection, the lungs were investigated for the presence of inflammation and of viral antigen by immunofluorescence and immunohistochemistry using a rabbit hyperimmune serum and monoclonal antibodies. Airway responsiveness was increased in the RSV group 1 week postinfection compared to the control group (PC0.1 mL CA median 2.50 vs >10 mg x mL(-1); p<0.001) and this persisted up to 5 weeks postinfection (PC0.1 mL CA median 1.61 vs >10 mg x mL(-1); p<0.001). During the same period, viral antigen persisted in the lungs of infected animals, although there was less inflammation at 6 weeks postinfection than at 1 week postinfection. In guinea-pigs, respiratory syncytial virus infection of the airways causes persistent airway hyperresponsiveness over a period of at least 5 weeks. During this time, viral antigen, but not inflammation, remains detectable in the lungs and might be responsible for ongoing airway hyperresponsiveness.

Animals↗
PubMed1996

Detection of respiratory syncytial virus (RSV) antigen in the lungs of guinea pigs 6 weeks after experimental infection and despite of the production of neutralizing antibodies.

Infections with respiratory syncytial virus (RSV) are characterized by frequently occurring reinfections and are regarded to be responsible for bronchial hyperreactivity. In this report we describe a small-animal model suited to study RSV-induced pathogenesis and immune response. Guinea pigs are infected by inhalation of an RSV-aerosol. Lungs of infected animals show signs of a bronchiolitis at 7 days after the initial infection. Although neutralizing serum antibodies are synthesized viral proteins are still detectable at 6 weeks post infection. Therefore, the presence of neutralizing antibodies is obviously not sufficient for rapid clearance of persistent RSV-proteins from the lungs of infected guinea pigs.

Animals↗
PubMed1996

Rotavirus infection and bradycardia-apnoea-episodes in the neonate.

UNLABELLED: Rotavirus (RV), a common cause of infectious enteritis in young children including neonates, has not been associated with central nervous symptoms in standard textbooks. However, involvement of the CNS has been reported recently in case reports and small series. From 786 neonatal admissions in 1991 we retrospectively analysed the records of 215 inpatient neonates (68 preterm and 147 term infants) who developed diarrhoea during their stay on the neonatal ward and in whom stools were investigated for RV antigen by ELISA. All 215 neonates were continuously monitored for bradycardia-apnoea-episodes (BAE) at least 2 days before and during the entire diarrhoeal period. In neonates with RV antigen in stools (n = 114) we found a higher incidence of BAE compared to neonates with RV negative stools (33% vs 8%, P < 0.001 for bradycardia; 7% vs 0%, P < 0.05 for apnoea). Furthermore, bradycardia episodes of RV positive neonates were more often followed by cyanosis (11 vs 0%, P < 0.05) and intervention was more often necessary (31 vs 14%, P < 0.05) than in the RV negative neonates. CONCLUSION: RV infection was associated with a high incidence of BAE in neonates with diarrhoea during the acute phase of disease suggesting CNS involvement.

Apnea↗
PubMed1996

Formaldehyde exposure enhances inhalative allergic sensitization in the guinea pig.

Formaldehyde (FA), a common indoor air pollutant, has been associated with increased prevalence rates of asthmatic symptoms among exposed individuals in epidemiologic surveys. We studied the influence of FA exposure on inhalative allergic sensitization in the guinea pig. Three groups of guinea pigs (n = 12 each) were exposed to clean air or two different FA concentrations (0.13 and 0.25 ppm) over 5 consecutive days. Exposure was followed by inhalation of 0.5% ovalbumin (OA) as sensitizing allergen. Three weeks later, specific bronchial provocation with OA was performed with body plethysmographic measurement of compressed air (CA). Furthermore, specific anti-OA-IgGl (reaginic) antibodies were determined in serum. In a further six animals, the respiratory tract was examined histologically for signs of inflammation directly after the end of FA or clean air exposure. In the group exposed to 0.25 ppm FA, 10/12 animals were found to be sensitized to OA (positive reaction on specific provocation) vs. 3/12 animals in the control group (P < 0.01). Furthermore, CA measurements of specific bronchial provocation and serum anti-OA-antibodies were significantly higher in the 0.25 ppm FA group than in controls (CA 0.35 vs. 0.09 ml median, P < 0.01; anti-OA-IgGl 13 vs. < 10 EU median, P < 0.05), indicating enhanced sensitization. In the group exposed to 0.13 ppm FA, no significant difference was found compared to the control group. There was no sign of inflammation of the lower airways in FA-exposed guinea pigs other than mucosal edema, which was discovered by morphometry. We conclude that short-term exposure to a low concentration of FA (0.25 ppm) can significantly enhance sensitization to inhaled allergens in the guinea pig.

Allergens↗
PubMed1996

Parainfluenza-3-virus infection enhances allergic sensitization in the guinea-pig.

BACKGROUND: Viral respiratory tract infections have been previously considered to be associated with induction of allergic sensitization. OBJECTIVE AND METHODS: In order to investigate this relationship in an animal model, guinea-pigs were inoculated intranasally with Parainfluenza-3-(PI-3) virus (n = 16) or virus-free culture medium (controls, n = 12), sensitized at day 4 with inhaled ovalbumin (OA) and challenged 3 weeks later with inhaled OA using specific bronchial provocation testing with body plethysmographic measurement of compressed air (CA). Furthermore, specific anti-OA-IgG1-antibodies in serum before challenge were determined by enzyme linked immunosorbent assay (ELISA). For investigation of airway epithelium permeability horseradish peroxidase (HRP) was inhaled at day 4 after inoculation by six animals, and HRP serum concentrations were determined by a direct ELISA 30 min after inhalation. RESULTS: PI-3 infected animals were found to be significantly more sensitized to OA compared with controls, with higher CA values (P < 0.001) on specific bronchial provocation and with increased specific anti-OA-IgG1 titers. Serum-HRP concentrations were about 20 times higher in the infected animals compared with controls. PI-3 infected and sham-infected animals had comparable bronchial reactions on specific provocation with OA when sensitized systemically. CONCLUSIONS: We conclude that viral respiratory tract infection with PI-3 virus enhances inhalative allergic sensitization in the guinea-pig. Increased mucosal permeability to antigens may be an important pathophysiological mechanism.

Adjuvants, Immunologic↗