Biomedical subjects

P Roth

Publications and source records attributed to P Roth.

At least 37 records · Page 2Linked to original sources

PubMed2003

Stable tracer investigations in humans for assessing the biokinetics of ruthenium and zirconium radionuclides.

The interest in the biokinetics of ruthenium and zirconium in humans is justified by the potential radiological risk represented by their radionuclides. Only a few data related to the biokinetics of ruthenium and zirconium in humans are available and, accordingly, the biokinetic models currently recommended by the ICRP for these elements are mainly based on data from animal experiments. The use of stable isotopes as tracers, coupled with a proper analytical technique (nuclear activation analysis with protons) for their determination in biological samples, represents an ethically acceptable methodology for biokinetic investigations, being free from any radiation risk for the volunteer subjects. In this work, the results obtained in eight biokinetic investigations for ruthenium, conducted on a total of three healthy volunteers, and six for zirconium, performed on a total of three subjects, are presented and compared to the predictions of the ICRP models.

Administration, Oral↗

PubMed2003

Developments in internal monitoring techniques.

In an effort to increase accuracy and speed, improve detection limits and reduce uncertainties in internal dosimetry, laboratories have developed improved or new internal monitoring techniques in both in vivo measurements and bioassay analyses. Most of these techniques have not yet entered routine monitoring programmes. This paper intends to summarise these new techniques, show their potential improvements compared to the currently employed monitoring routines and discuss the main aspects of the EC-funded IDEA project, which aims at a comprehensive assessment of these techniques and the enhancements necessary to bring them to broader acceptance in the routine monitoring community.

European Union↗

PubMed2003

Estimation of human exposure to natural radionuclides using in vivo skull measurements.

In a preliminary study, in vivo skull measurements and in vitro urine measurements of 210Pb and nulU have been performed to find out the individual, chronic exposure to waterborne natural radionuclides of a small group of Finnish people. For their domestic water, the studied individuals use water from drilled wells containing elevated concentrations of natural uranium and its daughter nuclides ((234,235,238)U, 222Rn, (226,228)Ra, 210Po, 210Pb). Enhanced 210Pb and 235U activities were observed in several people. A positive correlation is observed between the U concentration in urine (microg d(-1)) and the number of counts (cpm) in the gamma ray energy peaks originating from the decay of 235U and 234Th respectively. Calibration of the detector set-up and the determination of background sources are in progress.

Child↗

PubMed2003

Effects of vitamin E supplementation during erythropoietin treatment of the anaemia of prematurity.

AIMS: To evaluate the effects of vitamin E supplementation on haemoglobin concentration and the requirement for transfusion in premature infants treated with erythropoietin and iron. METHODS: Randomised, double blind, placebo controlled trial. Thirty infants </=32 weeks gestation and </=1250 g birth weight, who were defined as stable based on minimal requirements for respiratory support and phlebotomy, and absence of major congenital anomalies were enrolled. All were treated with erythropoietin and iron, and were randomised to receive, in addition, either vitamin E 50 IU/day or placebo for eight weeks or until discharge, whichever came first. RESULTS: Despite higher vitamin E (alpha-tocopherol) levels in the experimental group in weeks 3 (49.0 v 28.1 micro mol/l) and 8 (66.2 v 38.5 micro mol/l), there were no differences in haemoglobin, reticulocyte count, iron concentration, or transfusion requirement. CONCLUSIONS: Oral vitamin E supplementation at 50 IU/day does not increase the response of preterm infants to erythropoietin and iron. Vitamin E obtained through standard nutrition may have been sufficient or higher doses may be required.

Anemia, Neonatal↗

PubMed2003

[Should associated intraoperative and/or postoperative photocoagulation be systematic during or after vitrectomy for proliferative diabetic vitreoretinopathy?].

PURPOSE: To analyze the results of vitrectomy in proliferative diabetic vitreoretinopathy and to check whether systematic intra- and/or postoperative photocoagulation is necessary in most cases. PATIENTS AND METHODS: We retrospectively reviewed 108 patient records (137 eyes) of vitrectomy performed for complications of proliferative diabetic vitreoretinopathy between 1982 and 2000. Fifty-eight percent of the patients were women. The average age was 44 years. Sixty percent of the patients presented with diabetes type 1. Only 39% of the eyes had complete preoperative panretinal photocoagulation. Preoperative visual acuity was lower than 2/200 in 81% of eyes, 27% presenting initially with traction retinal detachment involving the macula. The surgical technique used was segmentation-delamination. Endodiathermy was necessary in 45% of the eyes and intraoperative photocoagulation was not performed. Postoperative complementary photocoagulation was carried out in only 9% of the eyes. RESULTS: Results were analyzed with an average follow-up of 66 months. Anatomical success was obtained in 69% of the eyes, with 55% visual improvement. These results were unchanging at long-term follow-up in 95% of the eyes studied. Iatrogenic retinal breaks were observed in 8% of the eyes. Postoperative complications were dominated by single (8%) or recurrent vitreous hemorrhage (8%). The rate of postoperative neovascular glaucoma was approximately 5%. These results are similar to the rates reported by other authors using intraoperative endophotocoagulation. CONCLUSION: Intra- and/or postoperative photocoagulation should not be systematic but reserved for management of iatrogenic retinal breaks and also for extensive panretinal photocoagulation in recurrent vitreous hemorrhage.

Adult↗

PubMed2002

New methods for monitoring cerebral oxygenation and hemodynamics in patients with subarachnoid hemorrhage.

Radiographic cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH) do not reflect cerebral hemodynamics and oxygenation and may occur in the absence of clinical deficit and vice-versa. This report is to describe preliminary findings in further development of a non invasive method to estimate regional cerebral oxygenation and perfusion. Measurements were performed with a technique combining near infrared spectroscopy (NIRS) and indocyaningreen (ICG) dye dilution. Successful data analysis has been performed based on the decomposition in pulsatile and non-pulsatile components of NIRS absorption data collected before and during the passage of ICG through the vascular bed under the NIRS-detector. First measurements in patients with CVS suggest that the technique could become a powerful tool in the detection and treatment of CVS. This non invasive technique can be done at the bedside, it seems to be safe, easy to perform and less time-consuming compared to conventional techniques. The influence of extracerebral bone and surface tissue on cerebral NIRS signal has not been clarified yet. Therefore a new subdural NIRS probe has been developed, which gives the opportunity to measure directly the concentration of the chromophores in the brain without the influence of extracerebral contamination. In future comparative measurements with conventional NIRS probes on the scalp will allow to quantify and eliminate extracerebral contamination from the NIRS signal.

Adult↗

PubMed2002

Strategies for surgical management of cerebral aneurysms of special location, size and form--approach, technique and monitoring.

Special strategies are mandatory for optimal surgical management of aneurysms of special location, size and form. Approaches of extradural selective anterior clinoidectomy, partial occipital condylectomy, transpetrosal approach by anterior petrosectomy and supracerebellar transtentorial approach are discussed among them. Furthermore various types of temporary and permanent clipping procedures are discussed along with mention of intraoperative monitoring.

Craniotomy↗

PubMed2002

[Partial CO(2) rebreathing technique versus thermodilution: measurement of cardiac output before and after operations with extracorporeal circulation].

BACKGROUND: The NICO(2) monitor determines "pulmonary capillary blood flow" (Qpc) and cardiac output (Qt) using the "partial CO(2) rebreathing technique". The agreement between NICO(2) and thermodilution (TD) cardiac output was compared before and after cardiac surgery with cardiopulmonary bypass (CBP). In addition, the possibility of calculating the intrapulmonary shunt fraction (Qs/Qt) by combining data from the NICO(2) monitor and the TD was investigated. METHODS: In 32 patients measurements were made following induction of anesthesia ("pre-CBP"), 30 min after weaning from CBP ("post-CBP"), and 6-8 h after surgery ("post-OP"). Qt was determined by the NICO(2) monitor and TD, Qpc by the NICO(2) monitor, and Qs/Qt(O(2)) from the standard formula. An intrapulmonary shunt was calculated using Qpc(NICO(2)) and Qt(TD) according to the equation Qs/Qt=1-Qpc/Qt. Bland-Altman and regression analysis techniques were used for statistical evaluation. RESULTS: "Pre-CBP" there was a good agreement between Qt(NICO(2)) and Qt(TD) with both a bias and precision of -0.13+/-0.46 l/min and a correlation of r=0.88+/-0.47 ( p<0.001). In contrast, "post-CBP" and "post-OP" there was a lack of agreement for Qt (bias and precision: 0.97+/-1.05 l/min and -0.33+/-0.8 l/min, respectively). Regarding the shunt calculations no significant correlations between methods could be found. CONCLUSION: Cardiac output measurement by the NICO(2) monitor agree well with TD under steady-state conditions but after CBP the agreement was too small. Combining Qpc(NICO(2)) and Qt(TD) does not offer a reliable possibility for calculating intrapulmonary shunt.

Algorithms↗

PubMed2002

Assessment of intestinal absorption of trace metals in humans by means of stable isotopes.

This study is aimed to demonstrate the feasibility of stable isotopes for the assessment of reliable data on fractional intestinal absorption of trace metals in healthy humans. Among the various methods available, the double isotope technique, i.e. one isotope given orally together with the test substance to be investigated and another isotope injected intravenously to correct for retention and endogenous excretion of the particular trace metal, provides quantitative figures of intestinal absorption at reasonable expenses with regard to costs for materials and number of samples to be evaluated. The trace metals exemplarily included in this study, i.e. iron, cobalt and molybdenum show diverging relations between absorbed fractions and amounts administered which are indicative for different regulatory mechanisms of their body content. Food ligands influence the fractional absorption significantly so that the uptake from a composite meal cannot be derived from results on uptake from particular foodstuffs. Therefore, validated data on the behaviour of intestinal absorption will significantly contribute to a better understanding of human trace metal metabolism.

Female↗

PubMed2001

Remote dipole effects as a means to accelerate [Ru(amino alcohol)]-catalyzed transfer hydrogenation of ketones.

A new generation of 2-aza-norbornyl amino alcohol ligands for the catalytic transfer hydrogenation reaction of aromatic ketones was synthesized. Extremely active catalysts were formed by introducing a ketal functionality at the rear end of the ligand. Acetophenone was reduced in 96% ee at low catalyst loading, substrate to catalyst ratio, S/C 5000, within 90 minutes with isopropyl alcohol as the hydrogen donor. It was found that the dioxolane substituent in the ligand increased the turnover frequency, TOF50, from 1050 h(-1) to 3000 h(-1) at an S/C ratio of 1000. Introduction of a methyl group at the carbinol carbon resulted in TOF50 as high as 8500 h(-1). Transfer hydrogenation of a range of aromatic ketones was evaluated and found to reach completion within 30 minutes at room temperature, and excellent enantioselectivity, up to 99 % ee, was obtained. A possible explanation for the enhanced activity was provided by density functional calculations, which showed that the presence of a remote dipole in the ligand lowered the transition state energy.

Journal Article↗

PubMed2001

Influence of continuous and discontinuous training protocols on subcutaneous adipose tissue and plasma substrates.

It has been shown that bouts of high-intensity exercise may reduce subcutaneous adipose tissue more than low-intensity exercise. The aim of the present study was to examine if a discontinuous training protocol is more successful in reducing adipose tissue than a continuous endurance training protocol. Fourteen untrained male volunteers were divided into two groups and trained for 10 weeks performing 3 discontinuous or 3 continuous workouts weekly (discontinuous exercise: 25 times 80 s 35% VO2max and 40 s 80% VO2max; continuous exercise: 50 min 50% VO2max). The discontinuous and the continuous training resulted in a similar subcutaneous adipose tissue loss, determined by skinfold measurement, in the leg above the patella (-2.4+/-2.4 and -2.4+/-1.4mm, respectively). The normalised plasma concentrations of free fatty acid, glycerol, beta-hydroxybutyrate, and lactate were similar throughout the final exercise test at the end of the training period. Our data suggested that the discontinuous protocol, selected so that the average intensity was similar to that of the continuous protocol, was not better than the latter in reducing subcutaneous adipose tissue.

Adipose Tissue↗

PubMed2001

Kinetics of systemic ruthenium in human blood using a stable tracer.

The biokinetics of ruthenium after oral and intravenous administration has been investigated in two human subjects using the stable isotope 101Ru as a tracer. Tracer concentrations in blood plasma have been determined using activation analysis with protons. The results presented here prove that the stable tracer technique is a valuable tool for obtaining relevant information about the biokinetics of ruthenium in humans. From these pilot studies, it may be argued that the clearance of systemic ruthenium from plasma is significantly slower than the predictions of the biokinetic model currently recommended by the International Commission on Radiological Protection (ICRP). The experimental data for the orally administered tracer, which reflect the gastrointestinal absorption process, differ from the curve derived from the ICRP model, suggesting that the uptake into the systemic circulation may be lower than predicted. On the basis of these preliminary data, investigations on a larger number of subjects with improvements in the experimental design are scheduled.

Administration, Oral↗

PubMed2001

Formation and in situ sizing of gamma-Fe2O3 nanoparticles in a microwave flow reactor.

Nanocrystalline gamma-Fe2O3 particles were produced in a microwave flow reactor. The reaction of iron pentacarbonyl [Fe(CO)5] with the plasma gases Ar/O2 to form nanosized particles was followed by in situ particle mass spectrometry. The particle mass spectrometer combines a nonintrusive sampling technique with a calibration-free mass determination. The influence of process parameters like microwave power, precursor concentration, and pressure on the particle size was studied. The results reveal a mean particle diameter in the range of 4-5 nm with a slight dependence on the process parameter. The geometric standard deviation of the measured size distribution was always between 1.1 and 1.2.

Crystallization↗

PubMed2001

Mapping the landscape: levels of transference interpretation.

The author argues that there are distinctly different kinds of transference interpretation, each of which might be valid in particular circumstances in analysis, but which contain and imply different understandings of what is meant by a 'transference interpretation'. She suggests that transference interpretations may be at any one of four different levels, and she describes these levels as ranging from interpretations that point to links between current events in the analysis and events from the patient's history, through interpretations that link events in the patient's external life to the patient's often unconscious phantasies about the analyst and the analysis, to interpretations that focus on the use of the analyst and the analytic situation to enact unconscious phantasy configurations, sometimes pulling the analyst into the enactment. Material from four consecutive sessions of an analysis is presented to illustrate how all levels of transference interpretation may be part of a lively and meaningful analysis, but how the level of interpretation may change as the level of understanding deepens within a session and from one session to the next.

Adult↗

PubMed2001

Supracerebellar transtentorial approach to posterior temporomedial structures.

The supracerebellar transtentorial (SCTT) approach, a modification of the infratentorial supracerebellar approach, facilitates simple and minimally invasive access to posterior temporomedial structures without requiring retraction of the temporal or occipital lobe. The SCTT approach was used in 16 patients over a 3-year period. Eleven patients harbored tumors confined to, or located mainly within, the posterior hippocampal formation, three patients harbored aneurysms (one ruptured posterior cerebral artery [PCA] aneurysm at the P2-P3 junction, one ruptured giant PCA [P2] aneurysm, and one giant basilar artery-superior cerebellar artery aneurysm), one patient had juvenile-type moyamoya disease, and one patient suffered from medically intractable epilepsy. In these patients, the SCTT approach enabled tumor removal, aneurysm clipping, and vascular bypass procedures. The authors' experience suggests that this approach can be used routinely in treating lesions in the posterior temporomedial region.

Adolescent↗

PubMed2001

[An appreciation of maternal smoking with high-performance liquid chromatographic determination of maternal and neonatal urinary cotinine].

OBJECTIVE: To study the correlation of urinary cotinine levels in mothers and newborns with the number of cigarettes smoked at the end of pregnancy. Population and methods. We recorded the smoking habits of 123 mothers attending a university maternity clinic and measured urinary cotitine levels in mothers and their newborns. All mothers were Europeans and gave birth to a normal full-term (37 weeks gestation) infant. Cotinine levels were measured with high-performance liquid chromatography from urine samples taken during the 6-hour period prior to or after delivery for the mothers and 24-h after birth for the newborns. RESULTS: The average cotinine level for non-smoking mothers, for those who smoked one to nine cigarettes a day and heavy smokers (ten or more cigarettes per day) were 0.21, 2.17 and 4.28 mol/l respectively (p<0.001). The average levels in their newborns were 0.04, 0.39 and 1.36 mol/l respectively (p<0.001). Thirteen percent of the mothers who claimed they did not smoke had cotinine levels higher than the significance cut-off (0.3 mol/l). There was a significant correlation 1) between the number of cigarettes the mothers stated they smoked at the end of pregnancy and their urinary cotinine concentrations (cotinine level=0.213 + 0.349 cigarettes, r=0.78, p<0.001); 2) between the number of cigarettes smoked and newborn's urinary cotinine concentration (cotinine level=0.002 + 0.104 cigarettes/day, r=0.81, p<0.001); and 3) between the mother's and the newborn's urinary cotinine concentrations (newborn cotinine=0.027 + 0.219 maternal cotinine, r=0.77, p<0.001). CONCLUSION: The number of cigarettes smoked at the end of pregnancy accounts for roughly 50% of the variance in the mother's urinary cotinine level and that in her newborn at birth. The urinary cotinine concentration in newborns is 3 to 5 times lower than that of their mothers. A woman smoking 3 cigarettes per day has a urinary cotinine concentration of 1 mol/l. The urinary cotinine level in newborns is 1 mol/l for mothers smoking 10 cigarettes per day.

Chromatography, High Pressure Liquid↗

PubMed2000

Comparison of human papillomavirus DNA testing and repeat Papanicolaou test in women with low-grade cervical cytologic abnormalities: a randomized trial. HPV Effectiveness in Lowgrade Paps (HELP) Study No. 1 Group.

BACKGROUND: Results of cervical cytology screening showing atypical squamous cells of undetermined significance (ASCUS) or low-grade squamous intraepithelial lesions (LSIL) indicate risk for high-grade cervical intraepithelial neoplasia (CIN 2 or 3). In a community-based randomized trial we compared the test performance of human papillomavirus (HPV) DNA testing with that of 6-month repeat Papanicolaou (Pap) test in detecting histologically confirmed CIN 2 or 3. METHODS: We randomly assigned 212 women aged 16-50 years with ASCUS or LSIL on cervical cytology screening to undergo either immediate HPV DNA testing or a repeat Pap test in 6 months. Cervical swabs for the HPV DNA testing and the Pap smears were obtained by their family physicians. We tested the swabs for oncogenic HPV using the Hybrid Capture II assay (Digene Corp., Beltsville, Md.). Community-based pathologists examined the Pap smears. All women were referred for colposcopy by their family physicians. Two gynecological pathologists assessed the histology findings. We calculated test performance in women who completed the trial using CIN 2 or 3 as the reference standard. RESULTS: A total of 159 women completed the study. Compared with HPV DNA testing, which detected 87.5% (7/8) of the cases of CIN 2 or 3, repeat Pap smear showing high-grade intraepithelial neoplasia (HSIL) detected 11.1% (1/9) of cases (p = 0.004), and repeat Pap smear showing ASCUS, LSIL or HSIL detected 55.6% (5/9) (p = 0.16). Corresponding specificities were 50.6%, 95.2% (p = 0.002) and 55.6% (p = 0.61). Loss to follow-up was 17.1% in the HPV test group and 32.7% in the repeat Pap group (p = 0.009). Given the 7 cases of CIN 2 or 3 detected by HPV testing and the 5 cases detected by the repeat Pap smear, the incremental cost of HPV testing was calculated to be $3003 per additional case of CIN identified. INTERPRETATION: HPV DNA testing was more costly but was associated with significantly less loss to follow-up. It may detect more cases of CIN 2 or 3 in women with low-grade cytologic abnormalities.

Adolescent↗

PubMed2000

Comparison of self-collected vaginal, vulvar and urine samples with physician-collected cervical samples for human papillomavirus testing to detect high-grade squamous intraepithelial lesions.

BACKGROUND: Certain types of human papillomavirus (HPV) in cervical samples are strongly associated with squamous intraepithelial lesions (SIL) and invasive cervical carcinoma. We determined and compared the test characteristics of testing for HPV with samples obtained by patients and with samples obtained by their physicians. METHODS: In a consecutive series of women referred to a colposcopy clinic at a teaching hospital because of abnormalities on cervical cytologic screening, 200 agreed to collect vulvar, vaginal and urine samples for HPV testing. The physician then collected cervical samples for HPV testing, and colposcopy, with biopsy as indicated, was performed. Presence of HPV was evaluated using the hybrid capture II assay (Digene Corp., Silver Spring, Md.) with a probe cocktail for 13 carcinogenic types. Cervical specimens were also tested for HPV by polymerase chain reaction and hybridization with type-specific probes. Cervical smears for cytologic examination were obtained from all women. RESULTS: High-grade lesions (high-grade squamous intraepithelial lesions [HSIL], equivalent to cervical intraepithelial neoplasia [CIN] grade 2 or 3, and adenocarcinoma) were found in 58 (29.0%) of the 200 women. Carcinogenic types of HPV were detected in the self-collected vaginal samples of 50 (86.2%) of these 58 women, in the self-collected vulvar samples of 36 (62.1%) and in the self-collected urine samples of 26 (44.8%). Carcinogenic types of HPV were detected in the cervical samples collected by physicians for 57 (98.3%) of these 58 women. The remaining 142 women (71.0%) had normal findings or low-grade squamous intraepithelial lesions (LSIL, CIN grade 1). Test results were negative or noncarcinogenic types of HPV were detected in the self-collected vaginal samples of 76 (53.5%) of these 142 women, in the self-collected vulvar samples of 89 (62.7%) and in the self-collected urine samples of 99 (69.7%). The sensitivity for self-collected samples ranged from 44.8% to 86.2%, and the specificity from 53.5% to 69.7%. For the samples collected by physicians, the sensitivity was 98.3% and the specificity 52.1%. The self-sampling methods were generally acceptable to the women: 98.4% of respondents (126/128) deemed urine sampling acceptable, 92.9% (118/127) found vulvar sampling acceptable, and 88.2% (112/127) found vaginal sampling acceptable. INTERPRETATION: Self-collection of samples for HPV testing was acceptable to women attending a colposcopy clinic for investigation of suspected cervical lesions and shows sufficient sensitivity to warrant further evaluation as a screening test for cervical cancer prevention programs.

Adenocarcinoma↗