Search PubMed⌕ Search

Biomedical subjects

J Ammon

Publications and source records attributed to J Ammon.

At least 19 recordsLinked to original sources
PubMed1998

Relation between occupational asthma case history, bronchial methacholine challenge, and specific challenge test in patients with suspected occupational asthma.

Inhalative methacholine challenge (MC) was performed in 229 subjects presumed to suffer from occupational asthma due to exposure to airborne latex allergens (n = 62), flour (n = 28), isocyanates (n = 114), or irritants in hairdressers' salons (n = 25). They were also subjected to specific challenges with the occupational agents they were exposed to, completed a questionnaire using an abbreviated version of the ATS-DLD, and were interviewed by an experienced physician. Bronchial hyperresponsiveness in MC was defined by the results obtained in a previous study with 81 healthy volunteers. The threshold in these controls was set at a cumulative MC dose of 0.3 mg, corresponding to a sensitivity of 95%. The main purpose of the study was to investigate whether the MC and/or the occupational asthma case history are reliable predictors of the specific challenge test outcomes. In 40-72% of examined subjects, workplace-related asthma complaints occurred, with bronchial hyperreactivity in the MC ranging from 48% to 61%. However, only 12-25% demonstrated a significant bronchoconstructive reaction in the specific challenge test. MC results are only moderately associated with workplace-related asthma case histories. Positive outcomes of challenges with occupational agents are well correlated with positive MC results plus occupational asthma case histories. The combination of MC and occupational asthma case history shows a relatively high specificity (62%, 86%, 80%), but the sensitivity was moderately low (83%, 71%, 52%). MC sensitivities were 92%, 71%, and 62% (case histories of hairdressers were not available). We conclude that in most cases, occupational asthma (as defined by a specific challenge test response) is combined with bronchial hyperresponsiveness and workplace-related asthmatic symptoms. However, subjects of each exposure group demonstrated bronchial hyperresponsiveness and complained of workplace-related asthmatic symptoms, but occupational asthma could not be proved in the specific challenge test. In subjects with a positive occupational asthma case history, a negative MC test result can almost rule out a positive specific challenges test result. Hence, the MC test can reduce performance of the laborious specific challenge test.

Adult↗
PubMed1995

[10 years' experiences with an innovative irradiation technic in breast carcinoma. An analysis of the late sequelae in normal tissue].

PURPOSE: In "high risk" breast cancer patients radio- and chemotherapy or hormonal strategies are applied after mastectomy. To reduce the risk of hot spots we developed an innovative irradiation technique using only 2 portals to encompass the chest wall and the regional lymph node areas. PATIENTS AND METHODS: In a retrospective analysis we evaluated 131 patients concerning late normal tissue reactions. We compared one group of combined treated patients (radio- and chemotherapy) with women who only had irradiation after surgery. RESULTS: The most frequent findings are telangiectasia in the chest wall (electron portal): grade 3 (1.5%), grade 2 (4.6%), grade 1 (35.8%), 58% no telangiectasia. A moderate lymphoedema of the arm was seen in 4.5%. There was no statistically significant difference between the 2 groups. CONCLUSION: Our treatment concept allows simultaneous application of radio- and chemotherapy without enhancement of late normal tissue reactions.

Breast↗
PubMed1995

[Pilot project for evaluation of lung function reference values].

Lung function tests were performed in this study on 139 adults (mean age 36 years), as well as on 91 female persons between 16 and 18 years of age (the latter just starting on their professional careers), the lungs being healthy in each case in both groups. The findings were compared with the currently accepted reference value formulae after Quanjer et al., and Zapletal as well as further developed reference value formulae after Brändli et al., Most of the measurement data obtained by spirometry for the BGFA group of probands are between the two recommended reference values for adults with better coincidence with Brändli's predictions (exceptions being MMEF25-75 MEF 50 and MEF 25). In our studies we obtained higher values than the reference median values after Quanjer and Zapletal for IVC, FVC, FEV1 and PEF by 6-8% and 5-15%, respectively, whereas the values for adults differ from the predictions made by Brändli et al. by -4% to +5%. The flow data MMEF 75-25, MEF 50 and especially MEF 25 are set at too low levels (by 5-23%) by Zapletal's and Brändli's values. Comparatively, the values predicted by Quanjer et al. for the above mentioned flow-volume parameters (with the exception of MEF 75) are too high by 4% to 12%. There are also considerable differences in respect of the reference values for IGV to the tune of +15% in the BGFA group compared to Quanjer et al.; in the BAFAM group the values differ from those of Zapletal et al. by +17%. RV yields results in the BGFA group which are higher by 11% than according to Quanjer's formulae, whereas in the BAFAM group they are higher by 15% compared to Zapletal's predictions. In respect of Rt there are differences to the predictions by Rühle and Matthys by +16% (BGFA group) and +13% (BAFAM group), respectively. The BAFAM group differs from Zapletal's predictions by +11%. Looking at the reference limit values the overall impression is confirmed that the predictions after Quanjer et al. and mostly also those by Zapletal are too low in respect of the abovementioned lung function parameters (in the majority of cases not 5% of the examined probands, as expected, are below those levels, but only about 2%). Females, who had been underrepresented in the previous healthy proband groups, show larger deviations than males in respect of most of the parameters.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1994

Respiratory and other hazards of isocyanates.

Isocyanates are increasingly being used for manufacturing polyurethane foam, elastomers, adhesives, paints, coatings, insecticides, and many other products. At present, they are regarded as one of the main causes of occupational asthma. The large number of workers who are exposed to these chemicals have a concentration-dependent risk of developing chronic airway disorders, especially bronchial asthma. Different pathophysiologic mechanisms are involved. Immunoglobulin E (IgE)-mediated sensitization and irritative effects have been clearly demonstrated in both exposed subjects and animals. Presumably, neural inflammation due to neuropeptide release of capsaicin-sensitive afferent nerves is crucial. We collected data on 1780 isocyanate workers who had been examined by our groups. Of them 1095 (including subjects from outpatient departments) had work-related symptoms, predominantly of the respiratory tract. Specific IgE antibodies were found in 14% of the 1095 subjects. The methacholine challenge test was shown to be an inadequate predictor of the results of inhalative isocyanate provocation tests in workers and in asthmatic controls. Isocyanate (toluene diisocyanate TDI) air concentrations of 10 ppb (0.07 mg/m3) and 20 ppb (0.14 mg/m3), respectively, did not cause significant bronchial obstruction in the majority of previously unexposed asthmatics with bronchial hyperreactivity. IgG-mediated allergic alveolitis, a rare disease among isocyanate workers, was found in approximately 1% of the symptomatic subjects. Experimental studies exhibit dose-dependent toxic effects and give evidence for tachykinin-mediated bronchial hyperreactivity after exposure to isocyanates. The clinical role of genotoxic effects of isocyanates and their by-products demonstrated here in vitro and in vivo has yet to be clarified.

Air Pollutants, Occupational↗
PubMed1994

An epidemiologic approach to predictors of elective coronary artery bypass mortality in a non-university hospital population.

This investigation was undertaken to determine whether perioperative variables present in patients scheduled for elective coronary artery bypass grafting (CABG) surgery, and documented in earlier studies at university programs, bear any significant relationship to mortality occurring in a population of prospectively monitored non-university hospital patients. The investigation sought to identify the risk factors that might be present in these patients. Toward this purpose, data from 1,095 patients having CABG surgery at four major non-university Pittsburgh hospitals were analyzed using univariate and multivariate analysis to develop a model for predicting survival. From this model, three variables, unstable angina or recent myocardial infarction (< 6 weeks); evidence of chronic heart failure at the time of the preoperative examination; and greater than 65 years of age were found to have high statistical significance (P < 0.02) in predicting mortality in this non-university-hospital population. In summary, the study demonstrated that three variables, previously confirmed as being valuable predictors of risk in university hospital populations, also have significant predictive value in elective non-university CABG survival.

Aged↗
PubMed1994

[Dosimetric studies using glass fibers].

PURPOSE: Ionizing radiation may cause discolouring of glasses by creation of colour centers. So radiation induced optical loss is a measure of absorbed dose. With a doped glass fiber a small volume optical dosimeter is developed for clinical purposes providing real time dosimetry with high spatial resolution. MATERIALS AND METHODS: Discolouring of glass by ionizing radiation is dose dependent and can be measured as light attenuation at a fixed wavelength. Light power of usual light emitting diodes (LED) is sufficient for this purpose. The readout light is conducted through a transmission fiber of arbitrary length. Concurrent measurements were performed at several wavelengths (660 to 850 nm) using a time multiplexing technique. We investigated the radiation induced light attenuation of a lead doped silica fiber with 60 Wt-% PbO2, diameter < 0.5 mm, and length < 0.1 m. The fiber was exposed to high energy photons of cesium-137, cobalt-60, 12-MV-photons, and 18-MV-photons generated by a linear accelerator, respectively. The influence of various temperatures, doses, and dose rates was tested. When sensor fiber is termed by a mirror reflected light can be detected with one transmission fiber and optical pathway is doubled. RESULTS: In a wide dose range (0 to 112 Gy) radiation induced loss represents absorbed dose in a linear manner without saturation effects. Optical loss is diminished by partial recovery of radiation damage depending on time and temperature. In order to compensate fading a phenomenological model was fitted to experimental data. Temperature dependence may be corrected by measurements with several readout wavelengths. Above 1 MeV there is merely a slight dependence on photon energy. At a size of the glass fiber reflection sensor of L = 2 cm doses of 0.04 Gy may be detected. The reproducibility at 1 Gy is about 4%. CONCLUSION: Lead doped silica fiber is suitable for radiation dosimetry in a dose range interesting for clinical practice. Fading may be compensated during irradiation using a phenomenological model. The size of a reflection sensor is comparable to thermoluminescence dosimeters. In contrast to TLD glass fiber provides real time dose measurements. By this means optical glass fiber dosimeter may be appropriate for in-vivo dosimetry in radiation therapy.

Glass↗
PubMed1993

Health risk in hospitals through airborne allergens for patients presensitised to latex.

Two nurses had to stop practicing because of severe work-related allergic respiratory or systemic symptoms. Both developed similar symptoms within a short time when they attended hospitals as outpatients or visitors or consulted a doctor or dentist, even when they had no direct contact with latex articles. The airborne latex allergen concentration in one room that induced symptoms was 128 ng per m3. In skinprick tests both women showed positive reactions to the phosphated cornstarch powder used to prevent latex gloves sticking together, but only when the powder had been in contact with latex. This powder seems a likely vehicle for the airborne latex allergen.

Adult↗
PubMed1993

[Effect of intraoperative radiotherapy on postoperative follow-up of pancreas cancer].

Surgical therapy alone has not been able to improve significantly long-term survival in cases of pancreatic carcinoma. Improvement can only be expected by more successful local and systemic tumor control. To achieve the former intraoperative radiotherapy (IORT) with high-energy electrons has recently been introduced into clinical practice. Between June 1989 und June 1991 23 patients underwent IORT while receiving palliative (n = 16) and curative (n = 7) procedures. During the same period 36 patients were operated upon without IORT. Irradiated patients suffered far more complications. A positive effect on survival or pain control in palliatively operated cases could not be demonstrated. Prolonged survival after curative resections with IORT seems probable but can not be proven due to small number of patients. Further progress requires combination of IORT with postoperative radiochemotherapy.

Adenocarcinoma↗
PubMed1992

A system for focal intracavitary irradiation of bladder cancer with remote iridium-192 afterloading.

An afterloading system for remote-control focal intracavitary irradiation of bladder cancer is presented. With 192Ir as radiation source, we demonstrated the practicability of the method in 23 chinchilla rabbits. A system for focal intracavitary irradiation of bladder cancer in humans was developed. A guiding tube with an inflatable balloon led to a reproducible vesical diameter. The intravesical part of the tube was shielded with lead and had a slit for focal radiation exposure. Three variant guiding tubes with different positions of the slit were designed to allow irradiation of any part of the bladder. The application is planned in patients with locally advanced tumors who refuse radical cystectomy or who are medically inoperable.

Animals↗
PubMed1991

[Computer-assisted placement for after-loading procedures with iridium 192].

Extremely high precision is needed to place radiation sources in the after-loading technique, but localisation techniques so far described do not offer the required accuracy. We used the computer-assisted surgery (CAS) localising system for the placement of after-loading probes in patients with head and neck carcinoma. Surgical instruments can be positioned without visual control using the CAS system. Since 1989 after-loading tubes have been placed using the CAS method. We evaluated the accuracy to be better than 1 mm. Ten after-loading treatments with iridium 192 of head and neck carcinomas were carried out between August 1989 and February 1991 with exact placement of the after-loading tubes in the nasopharynx. It seems feasible to treat cerebral tumours as well as tumours of the pelvic region by computer-assisted after-loading brachytherapy.

Adult↗
PubMed1991

[Portal films and daylight film developing].

Automatic daylight film handling systems in radiotherapeutic departments are useful to process simulation films. Plastic film cassettes with two polished stainless steel screens (2 mm at the front and 0.5 mm at the back) instead of the fluorescent intensifying screens are used. Regular diagnostic films are exposed with five monitor units. Loading and unloading of the cassettes are performed automatically. Exposed films are rapidly available with sufficient quality.

Automation↗
PubMed1990

[Detection of bone marrow involvement in breast cancer and malignant lymphoma using immunoscintigraphy of the hematopoietic bone marrow].

Radioimmunoimaging of bone marrow was performed for non-invasive detection of skeletal involvement in 15 patients with carcinoma of the breast and 17 patients with malignant lymphomas. Bone marrow scans were performed by means of a monoclonal 99mTc-labelled antibody, directed against NCA-95 and CEA. The presence and extent of skeletal involvement were controlled by skeletal scintigraphy, plain radiographs and CT; bone marrow biopsies were obtained in 19 patients as well. 20 subjects without suspected malignant disease served as controls. Haematopoietic bone marrow was imaged homogeneously and with high contrast in all controls. 15/15 patients with carcinoma of the breast and 10/17 patients with malignant lymphomas had multifocal bone marrow defects due to skeletal metastases. Bone marrow scans revealed significantly more lesions than skeletal scintigraphy both in carcinoma of the breast (p = 0.027) and malignant lymphomas (p = 0.015). Thus, radioimmunoscintigraphy of bone marrow may provide a new, sensitive approach for non-invasive detection of metastatic spread to the skeletal system.

Adult↗
PubMed1989

Radioimmunoimaging for diagnosis of bone marrow involvement in breast cancer and malignant lymphoma.

Granulopoietic bone-marrow was scintigraphically imaged in 15 patients with carcinoma of the breast and known skeletal metastases, 10 patients with malignant lymphomas, and 15 controls without suspected malignant disease, with a technetium-99m labelled murine monoclonal IgG1 antibody directed against nonspecific cross-reacting antigen (NCA-95) and carcinoembryonic antigen. Immunoscintigraphy revealed more lesions than did bone scanning in both patient groups. This method offers a sensitive, cost-effective, and easy-to-perform whole body technique for evaluating metastatic spread.

Antibodies, Monoclonal↗