Search PubMed⌕ Search

Biomedical subjects

P Roth

Publications and source records attributed to P Roth.

At least 19 recordsLinked to original sources
PubMed2006

[Prenatal diagnosis and management of a case of rapidly involuting congenital hemangioma. Review of literature].

Rapidly involuting congenital hemangioma (RICH) is a rare vascular lesion, identified in 1996, of elective localization in the dermal-hypodermic tissue. Its name comes from its particular natural course: it is fully developed at birth and then completely involutes, usually in the first year. We present a case of a RICH of the scalp discovered with a screening ultrasonography in the 31st week of gestation. We list the differential diagnoses. After birth, positive diagnosis lies preferably on pathology examination of a biopsy specimen in order to eliminate the hypothesis of a less favorable vascular lesion, teratoma or malignant tumor.

Adult↗
PubMed2006

The role of intraoperative monitoring of oculomotor and trochlear nuclei -safe entry zone to tegmental lesions.

OBJECTIVE: A safe entry zone to tegmental lesions was identified based on intraoperative electrophysiological findings, the compound muscle action potentials (CMAP) from the extraocular muscles, and anatomic considerations. This entry zone is bordered caudally by the intramesencephalic path of the trochlear, laterally by the spinothalamic tract, and rostrally by the caudal margin of the brachium of the superior colliculus. METHODS: Four intrinsic midbrain lesions were operated upon via the safe entry zone using the infratentorial paramedian supracerebellar approach. All lesions involved the tegmentum and included an anaplastic astrocytoma, a metastatic brain tumor, a radiation necrosis, and a cavernous angioma. CMAP were bilaterally monitored from the inferior recti (for oculomotor function) and superior oblique (for trochlear nerve function) muscles. RESULTS: In three of four cases, CMAP related to the oculomotor nerve were obtained upon stimulation at the cavity wall after removal of the tumor. Stimulation at the surface of the quadrigeminal plate, however, did not cause any CMAP response. Using this monitoring as an indicator, the lesions were totally removed. CONCLUSIONS: In the surgery of tegmental lesions, CMAP monitoring from extraocular muscles is particularly helpful to prevent damage to crucial neural structures during removal of intrinsic lesions, but less so to select the site of the medullary incision. The approach via the lateral part of the colliculi is considered to be a safe route to approach the tegmental lesions.

Action Potentials↗
PubMed2006

Methods for assessing gastrointestinal absorption of strontium in humans by stable tracer techniques.

Intestinal absorption of strontium from an oral test dose was studied in 13 healthy human volunteers using double tracer techniques with two stable strontium isotopes as tracers. Defined amounts of one isotope were administered orally, while tracer amounts of the second isotope were injected intravenously. Two different methods were used to assess the total fraction absorbed (f1 value). Fractional intestinal strontium absorption can be calculated from the ratio of the two isotopes in plasma or urine samples (in this paper called the double-isotope method) or the convolution integral technique, since both methods provide an accurate estimate of fractional absorption and yield comparable results. The latter additionally provides information on the absorption kinetics in the gastrointestinal tract. The absorption varies with respect to the chemical form and to the amount administered. Absorption patterns are characteristically different for uptake from solutions or from whole meals.

Administration, Oral↗
PubMed2005

Can default ICRP f1 values be applied to determine radiation dose from the intake of diet-incorporated thorium?

Data on the daily urinary excretion of thorium (Th) was obtained from 15 non-exposed adult German subjects. A radiochemical neutron activation analysis method was developed and standardised especially for this purpose. The daily urinary excretion of 232Th was found to be in the range 1.9-14.9 microBq d(-1) with a mean (+/-SD) value of 6.5 (+/-4.3) microBq d(-1). Using this excretion value and reported data on dietary intake of Th for a similar German population, the gastrointestinal absorption factor (f1 value) proposed by the International Commission on Radiological Protection (ICRP) was tested. Although the daily excretion of 232Th observed in the present study was comparable to some of the currently reported values in certain other countries, it was higher than the excretion value calculated by applying the biokinetic model of Th proposed by ICRP for the dietary intake values. The study showed that the default ICRP values of the f1 factor for diet-incorporated Th may not be applicable.

Adult↗
PubMed2005

Conventional microsurgical treatment of paraclinoid aneurysms: state of the art with the use of the selective extradural anterior clinoidectomy SEAC.

Surgical treatment of paraclinoid aneurysms is considered to be difficult due to their complicated anatomical location in the vicinity of important neural, vascular and bony structures. We present our clinical experience of the past 10 years of conventional microsurgical treatment of 81 paraclinoid aneurysms in 75 patients with the use of selective extradural anterior clinoidectomy SEAC and discuss the method of therapy option by reviewing recent reports on results of endovascular coiling method and the combination of these with conventional microsurgical therapy. The favorable surgical results with the use of SEAC and no recurrence of the treated aneurysm after clipping procedure in our series indicate that direct surgery can still be a standard technique for paraclinoid aneurysms in view of the fact that the endovascular aneurysm coiling methods are still associated with a considerable percentage of incomplete occlusion and present the problem of coil packing.

Blood Vessel Prosthesis↗
PubMed2005

Basilar bifurcation aneurysms. Lessons learnt from 40 consecutive cases.

Basilar bifurcation aneurysms are lately treated frequently with endovascular technique. Microsurgical clipping occlusion technique has, however, still its solid position because of its completeness. This standard technique is required often due to unfeasibility and/or incompleteness at the time of application of the endovascular technique for aneurysms of this location. The authors suggest following strategies and tactics for safe and secure occlusion of aneurysms of this location: pterional approach, selective extradural anterior clinoidectomy SEAC, no transection of the posterior communicating artery, isolation of perforating arteries at the time of neck clipping with oxycellulose and combination of the use of fenestrated clip and conventional clip (especially for aneurysms projected posteriorly), controlled hypotension (systolic pressure of around 100 mmHg), temporary clipping (trapping) procedures of usually less than 15 min. All these are aimed for prevention of intraoperative premature rupture, and of injury of perforating arteries and for complete occlusion of aneurysms in the narrow depth of the operative field.

Adult↗
PubMed2005

Validating an important aspect of the new ICRP biokinetic model of thorium.

The daily urinary excretion of Th (Th) was estimated in 11 adult German subjects who were not exposed occupationally to thorium and its related compounds. Thirty-one urine samples were collected over 24-h periods on different occasions from these subjects and were analyzed using high resolution sector field inductively coupled plasma mass spectrometry (HR-SF-ICP-MS). Using this instrument a limit of detection of 20 pg L for thorium in the reagent blank was achieved. The median (mean) daily urinary thorium excretion was obtained as 1.0 (1.8) ng. This was in good agreement with the mean value of 1.5 ng Th (6 microBq) reported by another group for German population, but is significantly lower in comparison to the daily excretion range of 3.6 to 105 ng reported from other countries. The expected daily urinary excretion of thorium for the adult German population was also calculated by applying the new ICRP biokinetic model of thorium assuming reference intake values. The expected urinary thorium excretion rate for this age group is about 0.1 ng per day. Even if a small contribution from the inhalation is considered, the calculated value will be much lower than the measured values. The reason for the disagreement appears to be the use of a low gastrointestinal absorption factor (f1) of 5 x 10 in the ICRP model. Based on the present study, a higher f1 factor might be proposed separately for dietary incorporated thorium.

Adult↗
PubMed2004

Near monochromatic X-rays for digital slot-scan mammography: initial findings.

X-ray spectra are composed of a broad bremsspectrum and anode-characteristic emission lines. In mammography typically molybdenum (Mo), rhodium (Rh) or tungsten (W) anodes are used in combination with Mo, Rh or aluminium filters. Only the photons with energies between 17 and 22 keV of the resulting spectrum are suitable for the soft tissue imaging needed for mammography. The aim of this article is to present first results obtained with a monochromator module mounted at the exit of the X-ray tube of a conventional clinical mammography unit. The experimental setup consists of a Siemens Mammomat 300, an X-ray monochromator module and a linear array detector for image acquisition. The technique is similar to the slot-scan technique known from digital mammography. The experimental machine allows to obtain images both with polychromatic and monochromatic X-rays. Initial evaluation of the system was performed by examination of a contrast-detail phantom (CD-MAM-phantom, Nijmegen, The Netherlands). Images done with the new monochromatic technique were compared to images of the phantom done with polychromatic spectra, with film-screen mammography as well as with digital mammography. The new technique with monochromatic slot-scan mammography resulted in correct identification of 93% of the phantom. Digital slot-scan mammography with polychromatic beam resulted in correct identification of 87%, digital full-field mammography in 83% and conventional film-screen mammography in 70% of the phantom. The results suggest that monochromatization has a potential for improving image quality or decreasing dose in X-ray mammography.

Equipment Design↗
PubMed2004

Solubility of airborne radioactive fuel particles from the Chernobyl reactor and implication to dose.

Airborne particles of nuclear fuel from the Chernobyl reactor that had been collected on air filters and stored, were characterised using in vitro dissolution tests to assess effective doses after their inhalation. As solvent, the Gamble biological fluid was used to simulate lung fluid. The solubility of the measured radionuclides decreased in the order (137)Cs>(90)Sr>>(241)Am>or=(239+240)Pu in the simulated lung fluid. The dissolution rate constant of e.g. (239+249)Pu ranged from 0.72 to 5.4 x 10(-6) g x cm(-2) d(-1) and decreased (for all nuclides) with increasing particle size as predicted from theoretical considerations. Considering the inhalation dose, decreasing dose with size and increasing doses with lower solubility may partly counterbalance each other for (137)Cs and (90)Sr. On the other hand, for (239)Pu and (241)Am larger particles and associated lower solubility both change the resulting dose in the same direction towards lower values. The comparison of the experimentally determined dose coefficients with ICRP values indicates that nuclear fuel particles closely resemble type M material characteristics for (137)Cs and (90)Sr and type S material characteristics for (239)Pu and (241)Am.

Aerosols↗
PubMed2004

Influence of the chemical form on the plasma clearance of ruthenium in humans.

The radioisotopes of ruthenium (103Ru and 106Ru) are abundant fission products and represent a radiological risk for the population in case of nuclear accidents. Few biokinetic studies have been performed on humans up to now and consequently the current model recommended by ICRP for ruthenium is derived mainly by extrapolation from animal data. The stable isotope 101Ru and proton activation analysis have been used to study the biokinetics of Ru in blood plasma samples taken during 8 studies in three healthy volunteers. The results obtained demonstrated that complexed Ru (in the form of citrate Ru(IV) complexes) is cleared from blood plasma very rapidly (characteristic half time of 17+/-2 min), while inorganic Ru remains longer in the systemic circulation, and is transferred to other organs and/or excreted with a biological half time of 23+/-2h. Good reproducibility of the clearance curves indicated no evidence of inter- or intra-individual variability when the same Ru solution was injected in repeated experiments to different subjects.

Adult↗
PubMed2004

[Benefits of ultrasonography in the delivery room].

Ultrasonography should benefit many pathological events which occur in delivery rooms. The authors analyse the scarce literature about this subject and propose indications in which this complementary examination seems to be interesting.

Breech Presentation↗
PubMed2004

Thorium and uranium contents in human urine: influence of age and residential area.

Inductively coupled plasma mass spectrometry (ICP-MS) has been used for the determination of (232)Th and (238)U in urine of unexposed Jordanian subjects living in six cities. The range of (232)Th excretion in all subjects was found to be 1.4-640 microBq d(-1) with an average of 34.8 microBq d(-1) (geometric mean 15.8 microBq d(-1)). Results showed no statistically significant correlation with age and residential area. The average value obtained is in agreement with levels considered normal in some recent publications. The average value of (238)U in all samples was found to be 3955 microBq d(-1) (geometric mean 1107 microBq d(-1)), which is higher than reported figures from Germany and India, but in agreement with those figures given in ICRP publication, number 23. The mean values of the different groups were found to be proportional to age up to 60 years. A noticeable drop is observed for subjects greater than 60 years old.

Adolescent↗
PubMed2004

Strontium biokinetics in humans: influence of alginate on the uptake of ingested strontium.

Radioactive isotopes of strontium, mainly 90Sr, released into the environment due to nuclear accidents may contribute significantly to the internal radiation exposure of members of the public after ingestion of strontium with contaminated foodstuffs. The committed radiation dose is significantly dependent on the fraction of the ingested activity that crossed the gut wall (f1 value). In tracer kinetic investigations, the effect of sodium alginate on the gastrointestinal absorption of strontium was studied in human subjects. Sodium alginate was proven to be a potent agent for reducing strontium absorption with high efficiency and virtually no toxicity. The data obtained show that the uptake of ingested strontium from milk was reduced by a factor of nine when alginate was added to milk. It is concluded that alginate preparations are a suitable antidote against radiostrontium.

Administration, Oral↗
PubMed2003

Regional dependence of urinary uranium baseline levels in non-exposed subjects with particular reference to volunteers from Northern Italy.

Knowledge of the level of natural uranium (U) in the human body is fundamental in order to estimate the potentially hazardous incorporation in accidentally exposed subjects. A constant monitoring of exposed workers needs reliable reference baseline values, which can be determined by measuring the U concentration in urine. ICPMS has proven to be a fast, reliable and highly sensitive technique for this purpose. Non-uniformity in the distribution of U levels in various regions and differences in dietary habits account for the significant regional variations of U concentration in urine in non-exposed subjects. In this paper, the determination of daily uranium urinary excretion levels in a group of 12 non-exposed subjects from Northern Italy is presented and compared to data present in the published literature and to values obtained in a larger group of German volunteers. The urinary U output values observed in the Italian subset are generally higher than the corresponding levels measured in other groups. This could be the result of a higher intake of U from liquids, as assessed by the determination of U concentration in drinking waters.

Adolescent↗
PubMed2003

A re-evaluation of the biokinetics of zirconium in humans.

There is much interest in understanding the biokinetics of zirconium in humans due to the potential radiological risk represented by the radionuclide 95Zr and by its daughter 95Nb. Despite the significance of zirconium, few data are available on the actual biokinetics of zirconium in humans. Accordingly the biokinetic model currently recommended by ICRP for this element is based mainly on data from animal experiments. In this study, the use of the stable isotopes 90Zr and 96Zr as tracers has enabled the conduct of 6 biokinetic investigations in 3 healthy volunteers. These studies have provided new valuable information about intestinal absorption and kinetics in blood plasma of zirconium and have been used for the set-up of a more realistic compartmental model with possible applications for dosimetric purposes.

Adult↗
PubMed2003

Intracellular adhesion molecule-1 in patients developing pulmonary insufficiency after cardiopulmonary bypass.

OBJECTIVES: Cardiopulmonary bypass activates adhesion molecules, which are associated with systemic inflammation and organ dysfunction. The intracellular adhesion molecule-1 (ICAM-1) has been evaluated in patients presenting pulmonary dysfunction after cardiac surgery. MATERIALS AND METHODS: Postoperative serum levels of the ICAM-1 were measured in 40 patients who underwent isolated coronary artery bypass grafting, in 28 with uneventful postoperative recovery (70 %) (Group 1), and in 12 (30 %) with postoperative respiratory insufficiency (Group 2), defined by the need for prolonged (> 24 hours) mechanical ventilation using a fractional oxygen concentration of > 40 %. RESULTS: Patients in group 1 were ventilated for 12.21 +/- 4.86 hours and those in group 2 for 92.91 +/- 48.14 hours (p < 0.001). ICAM-1 decreased from 145.98 +/- 73.40 ng/ml to 81.15 +/- 114.82 ng/ml in group 1, while in group 2 ICAM-1 showed a significant higher level and increased to 435.01 +/- 130.02 ng/ml (p < 0.001). The leukocyte count increased in both groups as well as the C-reactive protein (CRP) during the postoperative course. The CRP behaves similar in both groups (p = 0.636) in contrast to the leukocyte count which was significantly higher in group 2 (p < 0.01). While none of the patients in group 1 died the mortality in group 2 was 50 % (p < 0.001). CONCLUSION: Respiratory insufficiency after cardiopulmonary bypass is associated with a distinct increase in the ICAM-1. The reason for the increase of the ICAM-1 in this small subset of patients has not been clarified.

Aged↗
PubMed2003

Assessment of exposure to depleted uranium.

In most circumstances, measurement of uranium excreted in urine at known times after exposure is potentially the most sensitive method for determining the amount of depleted uranium (DU) incorporated. The problems associated with this approach are that natural uranium is always present in urine because of the ingestion of natural uranium in food and drink, and that the uncertainties in the intakes as assessed from excretion measurements can be quite large, because many assumptions concerning the exposure characteristics (time pattern of exposure, route of intake, chemical form, solubility, biokinetics within the body) must be made. Applying currently available methods and instruments for the measurement of uranium in urine samples, DU incorporations of levels relevant with respect to potential health hazards can be detected reliably, even a long time after exposure.

Environmental Exposure↗