Biomedical subjects

P Roth

Publications and source records attributed to P Roth.

193 records · Page 11Linked to original sources

PubMedDate not supplied

Non-invasive glycaemia blood measurements by electromagnetic sensor: study in static and dynamic blood circulation.

In this paper, we present the results of non-invasive blood glycaemia measurements. The blood used in the measurements was calf blood. The measurement method uses an electromagnetic sensor based on eddy currents, which allows the detection of blood glycaemia levels through the variation of the dielectric parameters of the blood. A change in blood glucose concentration causes a variation in the dielectric parameters, in particular conductivity. Detection is only possible at a resonant frequency. The measurements were taken in a static and dynamic state (with and without circulation of blood). The blood is inside a plastic tube placed within the sensor and is surrounded by gelatine, which simulates muscular tissue. The plastic tube simulates the vein where blood circulation occurs. The in vitro results in both cases (static and dynamic) are provided. Under unfavourable conditions we can detect a change of +/- 2 g/l of glucose. We present and discuss these results.

Animals↗

PubMedDate not supplied

Factors influencing transperitoneal calcium balance during CAPD.

A dialysate containing a calcium concentration of 1.75 mmol/L has been the standard in CAPD for a long time. This concentration was chosen to achieve a positive calcium balance to suppress hyperparathyroidism. In the measurement of peritoneal calcium mass transfer, conflicting results have been published, with positive and negative calcium balances reported. These differences have been explained by differences in the filtration rate, and a negative correlation between the filtration rate and the peritoneal calcium mass transfer can be found. Whereas nearly all patients in this study had a negative calcium balance using a glucose solution of 3.86%, a wide variation was found for the 1.36% glucose solution. There were several patients who had a positive calcium balance despite a positive filtration rate. The explanation for this finding lay in differences in serum concentrations of calcium, and especially differences in the size of the total exchangeable calcium pool that contains the plasma calcium compartment. A negative correlation between peritoneal calcium balance and the size of the total exchangeable calcium pool could be demonstrated. This finding may explain the differences in the peritoneal calcium flux reported in the literature. As an enlargement of the exchangeable calcium pool correlates with the progression of vascular calcification, therapeutic efforts should be directed toward prevention of an enlargement of this pool.

Adult↗

PubMedDate not supplied

Ferrokinetic studies with stable isotopes as tracers.

A methodology for ferrokinetic studies based on the administration of iron stable isotopes was developed. Fractional plasma clearance and intestinal iron absorption in rabbits were determined using the double tracer technique. Three rabbits were given 58Fe solution intravenously and about 40 min later 57Fe solution orally. Blood samples were drawn at different times following administration. The analysis of the single iron isotopes content in plasma samples was made by proton nuclear activation. The results were compared with those obtained from the administration, to the same rabbits, of the radioactive isotopes 55Fe and 59Fe. The agreement was found to be satisfactory.

Animals↗

PubMedDate not supplied

An iron metabolism study in humans by means of stable tracers.

An investigation of iron metabolism in a female patient volunteer by administration of stable iron isotopes as tracers was performed. The applied methodology had already been tested in rabbits in comparison with radioactive tracer technique. The subject under study was given 58Fe solution intravenously and about 45 min later 57Fe solution orally. Ten blood samples were drawn at different times within 522 min from injection. Single iron isotopes content in plasma samples was determined by proton nuclear activation. A Compton suppressor system was utilized to improve the detector limits. The characteristic parameters of iron plasma clearance and of iron intestinal absorption were determined.

Activation Analysis↗

PubMedDate not supplied

Molybdenum metabolism studied by means of stable tracers.

An investigation on molybdenum metabolism by administration of molybdenum stable isotopes was performed. Fractional intestinal absorption was determined in animals by the double tracer technique. The investigated subjects were given an enriched solution of Mo-96 orally and, a few minutes later, an enriched solution of Mo-95 intravenously. Blood samples were drawn at different times following the tracer administration. The Mo-95 and Mo-96 contents in plasma samples were determined by proton nuclear activation. The described methodology offers a means for the study of molybdenum metabolism in humans without radiation risk.

Administration, Oral↗

PubMedDate not supplied

Influence of olive oil emulsions on dentin demineralization in vitro.

The effect of two different concentrations of olive oil emulsions on development of artificial caries-like dentin lesions under severe demineralizing conditions was investigated. Bovine dentin samples (n = 180) were ground flat, polished, divided into four groups, and subjected to three demineralization cycles per day. Samples were stored in one of the following solutions for 5 min prior to demineralization in a buffer solution (pH 5): Group 1: 50% oil emulsion (olive oil and distilled water); group 2: 5% oil emulsion; group 3: distilled water; and group 4: 1,500 ppm sodium fluoride. Daily up to 9 days, lesion depth (ld) and mineral loss (deltaZ) were determined by means of microradiography and analyzed by ANOVA and Tukey's studentized range test (p < or = 0.05). Lesion depth increased with time for all groups. Mineral loss increased in groups 1-3. A small but significant decrease in mineral loss was observed following treatment with lipid emulsions as compared to treatment with distilled water, but fluoride treatment was considerably more effective. Mean mineral loss (means +/- SD in vol% x microm) averaged over the study period was 4,368 +/- 1,599, 4,536 +/- 1,823, 4,849 +/- 1,798, and 789 +/- 177 for group 1, 2, 3, and 4, respectively. Ratio (deltaZ/ld) remained constant around 30 vol% for groups 1-3, but decreased for group 4. In conclusion, externally provided lipids have the potential to reduce dentin demineralization in vitro.

Analysis of Variance↗

PubMedDate not supplied

[Estimation of rate constant for dissolution of radioactive fuel particles].

Some theoretical of the experimental investigation of solubility of radioactive aerosols were examined. Filters, which were exposed during October-November 1987 in Pripyat town, were studied. Measurements on 22 November 1987 showed that an activity in the air was 12.1-20.8 mBq/m3 for 137Cs, 34.9-89.3 mBq/m-3 for 144Ce, 24.3-30.5 mBq/m-3 for 106Ru. Disperse structure of aerosol hot particles and the number of hot particles on each filter fragment was estimated by radiography. To determine a dissolution rate constant a static system with two 0.14 micron pore size membrane MFE filters (Dubna, Russia) enclosing fragments of Petryanov filters was selected. The composition was held in Gamble's solution lung fluid anf then in 0.1 mol/l HCl as dastic juice simulation. The activity of 90Sr, 238Pu, 239 + 240Pu, 241Am and 244Cm in aerosol filters and solutions was measured by radiochemical methods. It was shown that leaching of radionuclides from aerosol hot particles in lung fluid simulation decreases in line 137Cs > 90Sr >> 239 + 240Pu > or = 241Am, depending om particle diameter and time. Dissolution constants were presented. Dissolution of aerosol particles in 0.1 mol/l HCl is also shown (dissolution time was 3 days). A radionuclide transition to HCl solution decreases in line 90Am 241Am >> 137Cs > 239 + 240Pu. A transition degree reached 21% for 90Sr and extraction of 241Am was 3-17%.

Aerosols↗

PubMedDate not supplied

Altered pattern of calcium kinetics in hemodialysis patients after parathyroidectomy.

Six HD patients with severe secondary hyperparathyroidism (sHPT) underwent studies of calcium kinetics prior to and after parathyroidectomy (PTX) with autotransplantation. Postoperatively, patients received vitamin D and calcium supplementation. Before PTX, a markedly elevated bone turnover was found, with increased fluxes of calcium from plasma into the exchangeable calcium pool. This pool was three times larger than normal, indicating a high risk of extraosseous calcifications. Despite a marked fall in parathyroid hormone (iPTH) levels after PTX, bone cell activity was maintained, as indicated by elevated values for Ca retention. Although Ca efflux from plasma into other compartments of the exchangeable pools remained above normal, the size of the total exchangeable calcium pool markedly decreased after PTX, indicating that PTX with autotransplantation, followed by vitamin D therapy, can normalize bone turnover and shift the balance of calcium flux towards mineralized bone. Reduction in the exchangeable calcium pool may explain the clinical finding that extraosseous calcifications regress in some patients after PTX.

Adult↗

PubMedDate not supplied

Biosynthesis of cytochalasans. XI. New results on the incorporation of phenylalanine into cytochalasin D by Zygosporium masonii [1].

Incorporation of L-[2-2H]phenyl-[2-2H]alanine and L-phenyl-[2-13C, 15N]alanine into cytochalasin D by Zygosporium masonii involved the complete loss of both the alpha-2H- and the alpha-15N-atom. Incorporation of a mixture of L-phenyl-[15N]alanine and L-[U-14C]phenylalanine into cytochalasin D and protein amino acids (phenylalanine, leucine, isoleucine) was accompanied by a substantial loss of 15N with respect to 14C. These effects are attributed to rapid exchange reactions taking place while L-phenylalanine is part of the intracellular pool of amino acids. In addition, the medium- and concentration-dependent incorporation of the carbon skeleton of exogeneous D-phenylalanine into cytochalasin D is reported. In a peptone-based complex medium, D-phenyl-alanine is poorly incorporated. Throughout the whole concentration range (0-250 mg/l), the incorporation rates are less than 10% of those of L-phenylalanine. In a minimal medium containing NH4NO3 as nitrogen source however, D-phenylalanine is preferred over the natural enantiomer by a factor of 1.28 up to 6.78, depending on the concentrations of exogeneous D- and L-phenylalanine. These effects are attributed to the medium-dependent activities of different amino acid transport systems responsible for the uptake of D- and L-phenylalanine in Z. masonii.

Cytochalasin D↗

PubMedDate not supplied

Comparison of the Cytobrush and cotton swabs in sampling cervical cells for filter in situ hybridization detection of human papillomavirus types 16 and 18 DNA.

The Cytobrush was compared with the cotton swab for collecting samples used to detect human papillomavirus (HPV) types 16 and 18 DNA by filter in situ hybridization. The study design entailed collecting two endocervical and one vaginal fornix sample from each of 200 women admitted to a colposcopy clinic. No difference was found in the HPV positivity rates in samples obtained with the two collection instruments. There was good agreement (91.5%) in the detection of viral DNA between the first and second endocervical samples; however, 15% of the patients with positive samples had detectable DNA in their second sample only. Significantly fewer samples from the fornix contained detectable HPV-16 or HPV-18 DNA than did endocervical samples.

Cervix Uteri↗

PubMedDate not supplied

Evaluation of human monocyte function in vitro.

Mononuclear phagocytes play a role in immunologic phenomena as well as in defence reactions of the organism. It is therefore important that clinicians have possibilities of evaluating their functions. A combination of simple and reproducible methods was set up to make this evaluation possible. The tests described in this paper are performed using peripheral blood monocytes and include: (1) phagocytic capacity of Staphylococcus aureus and 51Cr-labelled sheep erythrocytes, (2) bactericidal capacity with S. aureus and (3) handling of 51Cr-labelled sheep erythrocytes after 18 h in culture. They explore both the afferent limb of the immune response and the capacity to remove and destroy foreign material. The results obtained from 45 normal subjects are reported.

Adult↗

PubMedDate not supplied

Calcium kinetic studies in patients on CAPD: improvement of secondary hyperparathyroidism without concomitant improvement of calcium turnover.

OBJECTIVE: An association between the development of low turnover osteopathy and the form of dialysis treatment, that is, continuous ambulatory peritoneal dialysis (CAPD), has been described. To examine the effect of a year-long CAPD treatment on calcium (Ca) turnover, 12 patients were studied prior to and one year after initiation of CAPD treatment with a dialysate calcium of 1.75 mmol/L. DESIGN: A prospective analysis. SETTING: Academic teaching hospital dialysis unit. PATIENTS: Twelve patients with an average age of 54.8 years (range: 23-76 years) at commencement of dialysis and after 13 months of CAPD treatment. MEASUREMENTS: Calcium kinetic studies were performed using two calcium isotopes: 45Ca as an oral tracer and 47Ca as an intravenous tracer. Measurements of plasma and whole body activities were performed over a four-week period. From these measurements, kinetic parameters describing calcium turnover in different compartments were studied. These measurements were repeated after a mean time of 13.4 months. Patients were not treated with vitamin D, but received aluminum- and calcium-containing phosphate binders, in order to keep inorganic phosphate below 2.0 mmol/L and calcium within the normal range. RESULTS: After one year on CAPD, serum levels of calcium increased from 2.2 mmol/L to 2.35 mmol/L. Inorganic phosphate also increased from 1.4 mmol/L to 1.9 mmol/L, despite increased use of oral phosphate binders. Serum levels of intact parathyroid hormone (IPTH) decreased from 51.2 pmol/L to 28.3 pmol/L. Alkaline phosphatase did not change, nor did serum levels of vitamin D. Despite improvement of serum IPTH levels and better control of serum calcium, the kinetic parameters describing calcium turnover in the different calcium pools did not improve. In addition, the calcium retention of bone remained below normal range and did not rise. Perhaps more importantly, the relationship between Ca efflux and Ca retention did not change. While Ca retention remained low, plasma Ca efflux was normal. This imbalance was seen at the beginning of CAPD and did not change under CAPD. CONCLUSION: These data demonstrate that, after one year of CAPD treatment without vitamin D treatment, calcium turnover did not improve, despite a significant fall in serum IPTH levels. Studies on a larger number of patients are warranted to verify these results.

Adult↗

PubMedDate not supplied

Congenital nephrotic syndrome presenting with cerebral venous thrombosis, hypocalcemia, and seizures in the neonatal period.

Congenital nephrotic syndrome, a rare form of nephrosis, presents during the first year of life. We describe the case of a patient seen on the fifth day of life with seizures, hypocalcemia, hypothyroidism, and cerebral deep venous thromboses. Whereas these are generally long-term complications of this disorder, they may also be the presenting features in the neonatal period.

Diagnosis, Differential↗