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Biomedical subjects

P Fritsch

Publications and source records attributed to P Fritsch.

At least 19 recordsLinked to original sources
PubMed2007

Uncertainties in doses calculated according to ICRP recommendations after inhalation of 239PUO2 and early chest monitoring.

This study estimates uncertainties in Pu biokinetics and effective doses calculated after an acute inhalation exposure to 239PuO2 according to ICRP recommendations (default values for aerosols size and PuO2 dissolution parameters). This was performed using the most recently reported variations in model parameters and simulations after a Monte Carlo approach. Without chest monitoring, uncertainties in thoracic retention and plutonium excretion was 8-10 (95% confidence interval as the ratio between 97.5 and 2.5 percentiles of the lognormal distributions) up to 900 d after exposure. Early chest monitoring reduces significantly the uncertainties in plutonium biokinetics and doses which remain within a 95% confidence interval of 2.3 as compared with 6.6, without monitoring. Analysis of bioassay data previously reported shows that the dose delivered to some individuals can be out of the confidence interval, which was mostly due to an inhibition of the late mechanical clearance of the alveolar interstitium.

Administration, Inhalation↗
PubMed2006

[Xanthoma disseminatum: a rare case involving the upper extremity].

We describe a dramatic case of class II non-Langerhans cell histiocytosis, xanthoma disseminatum, in a 30-year-old male patient with progressive involvement of the skin, vocal cords, eyes, bones and nerves in spite of chemotherapy with Vespesid and immunotherapy with interferon-gamma. At the age of 43 years, the patient required surgical clearance of airways, eyelids and peripheral nerves, but at present exhibits stable disease on a combination of lipid-lowering drugs including thiazolidinedione.

Adult↗
PubMed2006

Uncertainties in aerosol deposition within the respiratory tract using the icrp 66 model: a study in workers.

This study estimates uncertainties in aerosol deposition within the main regions of the human respiratory tract calculated using the ICRP 66 model. Uniform, triangular, normal, or lognormal distributions were assigned to the model parameters, which involve physical properties of aerosols, their inhalability, their thermo- and aerodynamic deposition efficiencies, and the anatomy, physiology, and exertion level of the individuals. Calculations were performed over a range of aerosol sizes from 0.01 to 50 mum. Monodispersed aerosols were characterized by their aerodynamic diameter (dae). Polydispersed aerosols were characterized by their activity median aerodynamic diameters (AMADs) and the geometric standard deviation (GSD) in diameter. Lognormal distributions of particle deposition were generally observed with low GSD (< 2). The highest uncertainties were observed within the deep lung for the smallest and the largest aerosol sizes, which were mainly due either to particle density or to aerodynamic deposition efficiencies and anatomical and physiological variability, respectively. In the case of diameters larger than 5 mum, uncertainties in the deep lung deposition were much more important for monodispersed than for polydispersed aerosols. This was explained both by the size distribution of the deposited aerosol, the median of which corresponded to a maximal dae value of about 7 and 5 in bronchioles and alveoli, respectively, and by the absence of deposition, which occurs for dae equal to or larger than 50 mum, depending on the exertion level. Thus, in the range of AMADs considered, for the four default workers proposed by ICRP 66, uncertainties in aerosol deposition remain low, with GSD smaller than 3.

Aerosols↗
PubMed2006

Sentinel lymph node status in melanoma: a valuable prognostic factor?

BACKGROUND: Sentinel lymph node (SLN) biopsy is advocated as the standard of care for patients with primary melanoma. It is a procedure with few side-effects and provides valuable staging information about the regional lymphatics. OBJECTIVES: To investigate the prognostic value of SLN biopsy and to compare it with that of other known risk factors in primary melanoma. METHODS: One hundred and forty-nine patients with primary melanomas (tumour thickness >1.0 mm) underwent SLN biopsy between May 1998 and April 2004 at our department. This report summarizes the follow-up data of this cohort until October 2004. RESULTS: SLN biopsies of 49 of 149 patients (33%) revealed micrometastatic disease. Of all clinical and histological criteria, only the clinical type of primary melanoma (11 of 19 patients with acrolentiginous melanomas) and the Clark level were predictive for SLN positivity. Progression was observed in 22 patients (15%). It was significantly associated with ulceration of the primary tumour, tumour thickness, clinical type and localization of the primary tumour, female sex and older age. In contrast, SLN positivity was not significantly associated with a higher risk of progression (eight of 49 SLN-positive vs. 14 of 100 SLN-negative patients; P = 0.807). Twelve of 149 patients (8%) died because of melanoma in the follow-up period. Significant criteria for death were ulceration of the tumour, clinical type and localization of the primary tumour, but not SLN positivity. CONCLUSIONS: A high percentage of positive SLNs was observed in the patients with melanoma in our study (33%). The fractions of patients both with progressive disease and with tumour-related death were not significantly higher in patients with positive SLN than in those with negative SLN. We therefore conclude that the SLN status is not a reliable prognostic factor for progression of melanoma.

Adolescent↗
PubMed2006

Multicentre, phase II trial on the safety and efficacy of topical tacrolimus ointment for the treatment of lichen sclerosus.

BACKGROUND: Lichen sclerosus is a chronic inflammatory autoimmune disease causing significant sclerosis, atrophy and pruritus. Treatment remains unsatisfactory, with potent corticosteroids being the most effective therapy. OBJECTIVES: To conduct a multicentre, phase II trial to assess the safety and efficacy of tacrolimus ointment 0.1% for the treatment of lichen sclerosus with a follow-up period of 18 months at 10 university and teaching hospitals in Germany and Austria. METHODS: Eighty-four patients (49 women, 32 men and three girls) aged between 5 and 85 years with long-standing, active lichen sclerosus (79 with anogenital and five with extragenital localization) were treated with topical tacrolimus ointment 0.1% twice daily for 16 weeks. Computerized analysis of the lesional area was performed. The primary endpoint was clearance of active lichen sclerosus. Secondary endpoints were time to optimal response, reduction of sclerosis and duration of remission. RESULTS: The primary endpoint (clearance of active lichen sclerosus) was reached by 43% of patients at 24 weeks of treatment. Partial resolution was reached in 34% of patients. Maximal effects occurred between week 10 and 24 of therapy. Treatment led to a significant reduction of the total lesional area (P < 0.01) and to a significant decline in the total symptom score (P < 0.005). Symptoms (e.g. itching) and findings (erythema, erosions and induration) showed significant improvement. No serious adverse events were observed. There were three (9%) recurrences during the follow-up period. CONCLUSIONS: Topical tacrolimus ointment 0.1% was safe and effective for the treatment of long-standing active lichen sclerosus.

Adolescent↗
PubMed2006

Thrombin generation in factor VIII-depleted neonatal plasma: nearly normal because of physiologically low antithrombin and tissue factor pathway inhibitor.

BACKGROUND: Bleeding in hemophilic neonates has a low incidence. A possible explanation for this could be the peculiarities of the neonatal hemostatic system, especially low levels of the inhibitors tissue factor pathway inhibitor (TFPI) and antithrombin (AT). OBJECTIVE: We investigated the influence of an elevation of these inhibitors to adult levels on the thrombin generation (TG) in normal neonatal plasma and factor (F) VIII-depleted neonatal plasma by means of incubation with anti-FVIII-antibodies. PATIENTS/METHODS: TG was measured after activation with low amounts of tissue factor (TF) by using Calibrated Automated Thrombography. RESULTS: TG in FVIII-depleted neonatal plasma was nearly as high as in normal neonatal plasma. TG decreased after elevation of AT in both neonatal plasmas. After elevation of TFPI TG decreased much more in FVIII-depleted neonatal plasma than in normal neonatal plasma. After elevation of both inhibitors their synergistic effect led to a stronger decrease of TG in FVIII-depleted neonatal plasma. TG measured in plasma of one hemophilic newborn showed the same pattern as in FVIII-depleted neonatal plasma. CONCLUSION: Our observation provides a biochemical basis for the rare bleeding in hemophilic neonates and shows the important role of the natural inhibitors in the hemostatic system of hemophilic patients.

Adult↗
PubMed2005

Absence of contact sensitization to Aloe vera (L.) Burm. f.

Aloe vera has been used as a cosmetic and medical remedy since ancient times and has gained increasing popularity in recent years. Despite its widespread use, reports of allergic reactions are rare. We patch tested 702 consecutive patients with an oily extract from the leaves, Aloe pulvis from the entire plant and concentrated Aloe vera gel. A specially designed questionnaire was used for the use of Aloe vera, reasons and location of application, adverse reactions, occupation, hobbies and atopy. None of the subjects showed any reaction to one of the preparations. 2 components of the plant have to be distinguished: the bark of the leaves contains anthrachinones with pro-peristaltic and potential antibiotic and anticancer properties. Constraints have been imposed due to their considerable toxic potential. Today, mostly the Aloe gel from the center of the leaves is processed. It almost exclusively consists of carbohydrates to which also many medical effects have been attributed. Carbohydrates are not likely to induce contact sensitization, which might explain the outcome of our study. However, this does not justify unrestrained promotion of Aloe products, as scientific studies investigating the claims on its constitutional effects are few in number, and the majority of them have been unable to diminish the intuitive scepticism against miracle cures, like Aloe seems to be.

Allergens↗
PubMed2004

Comparative tissue uptake and cellular deposition of three different plutonium chemical forms in rats.

PURPOSE: To evaluate the influence of the chemical form of plutonium (Pu) on its distribution in tissues and within liver cells populations. MATERIALS AND METHODS: Groups of male Sprague-Dawley rats were contaminated by intravenous injection of either Pu citrate, Pu nitrate or Pu phytate. Pu content was determined in various tissues at different times after injection. Pu liver distribution was analysed by autoradiography and after cellular separation. RESULTS: Biokinetic studies indicate that Pu citrate and Pu nitrate predominantly retained in the skeleton within the first hours after injection, whereas most of the Pu was in the liver after injection of Pu phytate. Autoradiographs showed that Pu citrate was homogeneously distributed in the liver, while Pu nitrate accumulated into 'hot points'. Pu phytate showed an intermediate distribution pattern. Hepatic cell separation revealed a difference of uptake between the two cell types depending on the chemical form of injected Pu, and on the time after contamination. CONCLUSIONS: Distinct Pu behaviour was observed for biokinetics, retention and liver distribution. The large differences noted between citrate, nitrate and phytate might be explained by differences in systemic and hepatic transport.

Animals↗
PubMed2004

Targeting of diethylene triamine pentaacetic acid encapsulated in liposomes to rat liver: an effective strategy to prevent bone deposition and increase urine elimination of plutonium in rats.

PURPOSE: To modify the distribution of the chelating agent diethylene triamine pentaacetic acid (DTPA) by using a formulation approach with liposomes in order to match the in vivo distribution of plutonium (Pu) and, as a consequence, to improve actinide decorporation. MATERIALS AND METHODS: DTPA was encapsulated in conventional and stealth liposomes. Their pharmacokinetics and ability to remove Pu were evaluated in rats 2 and 16 days after a single intravenous treatment given 2 h after contamination with colloidal Pu (239Pu phytate) or with soluble Pu (238Pu citrate). RESULTS: Both formulations induced major pharmacokinetic modifications in rats, allowing an accumulation of [14C]-DTPA mainly in the liver and secondarily (for stealth liposomes) in bone and spleen. These modifications were associated with major increases in urine elimination and with a decrease in skeletal Pu deposition, depending of the nature of the Pu contaminant. After contamination by Pu phytate, conventional liposomes of DTPA (6 micromol kg(-1)) were as efficient as free DTPA (30 micromol kg(-1)) in maintaining the Pu content in the femur below 4.3% of the injected dose after 16 days, a 3.6-fold reduction compared with free DTPA (4 micromol kg(-1)) treatment or without treatment. CONCLUSIONS: A formulation approach with liposomes appears to be a powerful tool to improve the efficiency of Pu chelating agents in vivo.

Animals↗
PubMed2004

Radionuclide biokinetics database (RBDATA-EULEP): an update.

The main activity of the RBDATA-EULEP project is the development of an electronic database of information on the biokinetics of radionuclides after intake by inhalation, ingestion or injection. It consists of linked tables of publications and experiments, with details and comments on the materials, procedures and results. By March 2004 it contained information on more than 1600 experiments from 600 publications. It will be extended and Internet access will also be provided.

Body Burden↗
PubMed2004

Uncertainties in doses due to the number of aerosol particles: study on 239PuO2 using default parameters for workers.

The behavior of individual particles has been taken into account to estimate, after inhalation, uncertainties in deposition fractions and doses due to the number of 239PuO2 aerosol particles. Using ICRP models and default parameters recommended for workers, similar results were obtained after calculation and after simulations of exposures to 500 to 3 x 10(6) particles (from about 1 Bq to 6 kBq). Uncertainties obtained from simulations increase as the number of particles decreases. The maximal uncertainties in the deposition fraction were observed for the sequestered regions in which no deposit often occurs for exposures of less than 1 x 10(5) particles. Similar large uncertainties in the number of nuclear disintegrations over 50 years were observed in the sequestered regions as well as in lymph nodes. For a given number of particles, uncertainties in committed equivalent doses gradually decrease from the extra-thoracic region to lymph nodes, bronchi, bronchioles, and alveolar interstitium. For 1 x 10(4) particles, similar uncertainties were observed for the committed equivalent doses delivered to lung, liver, bone surfaces, red marrow and gonads, and for dose per unit intake (DPUI), whereas for 1 x 10(5) particles and more, uncertainties in DPUI were higher than those in equivalent doses. The explanation is that in some simulations the maximal committed equivalent dose was delivered to the extra-thoracic respiratory tract region (in which case the DPUI calculation mode must be changed).

Air Pollutants, Radioactive↗
PubMed2004

Temozolomide and interferon alpha 2b in metastatic melanoma stage IV.

BACKGROUND: A multicentre, centrally randomized, open-labelled study with temozolomide and interferon (IFN)-alpha 2b was carried out to study the therapeutic effect in patients with metastatic melanoma stage IV. OBJECTIVES: The response rate, efficacy, side-effects, reasons for discontinuation of therapy and survival rate of 47 patients treated with temozolomide in combination with two different dosing regimens of IFN-alpha 2b were documented. PATIENTS/METHODS: Twenty-nine male and 18 female patients (mean age 57.6 years, range 34-74) were centrally randomized to two different arms: 20 patients received a treatment schedule with temozolomide 150 mg m(-2) on days 1-5 orally every 28 days in combination with IFN-alpha 2b 10 MIU m(-2) every other day and 27 patients received temozolomide 150 mg m(-2) on days 1-5 every 28 days in combination with IFN-alpha 2b in a fixed dose of 10 MIU every other day. RESULTS: We observed an overall response rate of 27.6% comprising five complete remissions (10.6%: one patient group A, four patients group B), in two of these five patients at the last follow-up in the study (4.3%, both in group B); and eight partial remissions (17%: six patients in group A, two patients in group B), in three of these eight patients at the last follow-up in the study (6.4%, two patients in group A, one patient in group B). Three patients showed stable disease (6.4%: one patient in group A, two patients in group B). Mean survival was 14.5 months [95% confidence interval (CI) 10-19] with no significant differences between treatment groups. However, there was a significant correlation with response after three cycles (log rank test, P < 0.03). Within the 32 patients who completed at least three cycles of therapy, seven patients (three in group A and four in group B) with a partial or complete response showed a significantly better mean survival of 30.6 months (95% CI 19.1-42) compared with 25 patients who did not respond (13.7 months 95% CI 9.2-18.3). In total, patients with at least one complete remission showed the longest survival (37.1 months 95% CI 26.3-47.9), followed by patients with at least one partial response (17.4 95% CI 10.9-23.9). Major side-effects of the treatment were nausea, vomiting, headache, leucopenia, thrombopenia, elevation of liver function parameters and neurological symptoms. In five patients, the side-effects led to a discontinuation of treatment: neurological symptoms (two patients), sepsis (one patient), brain haemorrhage (one patient) and exanthema (one patient). There were no treatment-related deaths. CONCLUSIONS: The combination of temozolomide and IFN-alpha 2b can easily be administered and shows tolerable toxicity. When an objective response occurs after three cycles, it indicates a significant survival advantage.

Adult↗
PubMed2003

Evaluation of risk factors for lung tumour induction in rats exposed to either NpO(2) or PuO(2) aerosols.

PURPOSE: To compare the incidence of each lung tumour type after inhalation exposure of rats to either NpO(2) or industrial PuO(2) aerosols, which have a similar size. MATERIALS AND METHODS: Male Sprague-Dawley rats were exposed once and followed during their whole life span. At the end of their life, the whole lungs were fixed, embedded and cut into thin sections for histological analysis. The presence of tumours was evaluated on three distinct levels of the lobes for phenotype determination to establish dose-effect relationships. RESULTS: In the range of lung doses studied (0.05 to more than 50 Gy), the general trend was an increased frequency of all types of tumours after inhalation exposure to neptunium compared with plutonium. The linearity of the lower part of the dose-effect relationships for all malignant lung tumours leads to the conclusion that NpO(2) is 3.3-fold more carcinogenic than PuO(2). CONCLUSIONS: According to a linear extrapolation of the data on malignant lung tumour incidence collected among all studies reported on actinide oxide carcinogenesis, the risk of lung tumour appears to vary over a factor of about 10 depending on the nature and/or size of the aerosol. This variation has to be taken into account for a realistic assessment of tumour risk.

Actinoid Series Elements↗
PubMed2003

Does mean lung dose calculated after inhalation of alpha emitters actually reflect the risk of induction of malignant lung tumours?

A comparison of incidence of lung tumours in rats after inhalation exposure to aerosols containing alpha emitters which have different physico-chemical properties has been performed. Aerosols of radon and progeny, uranium ore dust, NpO2, PuO2 or Cm2O3 were considered for intercomparison with similar or different particle sizes. Dose-effect relationships for the frequency of malignant lung tumours appear linear up to a few Gy and then become infralinear at higher doses delivered to the lungs. The initial slope of the curves reflects the risk of induction of a lung tumour. The highest slopes of incidence were observed for radon and uranium ore dust (about 70 and 20% Gy(-1) respectively) for which the most homogeneous alpha dose distribution to the lungs is expected. In a general trend, increasing the alpha-activity of deposited particles (higher specific activity of constituent radioisotopes or larger particle size) decreases the risk. The comparison of the reported data shows that the risk per Gy at 'low doses' could vary over more than one order of magnitude depending on the physico-chemical properties of the aerosols.

Actinoid Series Elements↗