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At least 235 records · Page 13Linked to original sources
PubMed1993

Peptide, protein, and cellular interactions with self-assembled monolayer model surfaces.

Model biomaterial surfaces with well defined chemistry were prepared from close-packed alkyltrichlorosilane monolayers on polished silicon and glass. The outermost molecular groups which come in direct contact with the biological environment were varied across a wide range of oxidation states by employing -CF3, -CH3, -CO2CH3, and -CH2OH terminal functionalities. Characterization by contact angles, surface spectroscopy, and ellipsometry verified that these model surfaces could be repeatedly prepared with good consistency for routine use to study biomolecule adsorption onto model surfaces. Adhesion of canine endothelial cells and the adsorption of proteins (human serum albumin and human fibrinogen) as well as series of synthetic defined oligopeptides to these model surfaces have been studied. Endothelial cells attachment and growth were in the rank order of: -CH2OH > -CO2Me > -CH3 > -CF3. The peptides were comprised of different alternating sequences of lysine, leucine, and tryptophan residues. These structural differences imparted different amphiphilic characters that led to measurable differences in the adsorption of these peptides to liquid-vapor interfaces. The adsorption to model surfaces was studied using ESCA, radiometry, and concentration-dependent contact angles. ESCA and radiometry measured irreversible biomolecules adsorption whereas the contact angle method measured steady-state adsorption. Radiometric results were inconsistent with ESCA, possibly due to artifacts associated with protein radiolabeling.

Adsorption↗
PubMed1995

Evaluation of a modified BACTEC method to study the activity of disinfectants against Mycobacterium tuberculosis.

SETTING: BACTEC radiometry could provide a useful tool for evaluating the effect of disinfectants on mycobacteria. OBJECTIVE: The aim of this study was to improve the recovery of mycobacteria in the BACTEC system and thereby develop a new method for disinfectant testing with Mycobacterium tuberculosis. DESIGN: Protein was added to BACTEC 7H12B media. Growth and the recovery of M. tuberculosis after exposure to disinfectants was measured using viable counts and BACTEC radiometry. RESULTS: Protein additives enhanced growth in 7H12B media. After serial dilution of inoculum, 7H12B plus 10% egg yolk recovered mycobacteria from a 10(-2) higher dilution than viable counts. After 5 min disinfection with 3% peroxygen compound (Virkon), 3% Virkon plus saline or 2% gluteraldehyde (Cidex) no mycobacteria were recovered using standard 7H12B. However, using 7H12B plus protein, growth was detected in all of these within 30 days. In contrast, viable counts detected growth with Cidex and Virkon after 5 min disinfection but not from Virkon in saline. Viable counts took 3-8 weeks to determine. CONCLUSION: Using this modified BACTEC system for the evaluation of disinfectant action on mycobacteria provides advantages in speed, sensitivity and ease of use when compared with viable counts.

Culture Media↗
PubMed1996

Imaging laser heated subsurface chromophores in biological materials: determination of lateral physical dimensions.

We describe a non-contact method using infrared radiometry to determine lateral physical dimensions of laser heated subsurface chromophores in biological materials. An imaging equation is derived that relates measured radiometric temperature change to the reduced two-dimensional temperature increase of laser heated chromophores. From measured images of radiometric temperature change, the lateral physical dimensions of chromophores positioned in an in vitro model of human skin are determined by deconvolution of the derived imaging equation using a non-negative constrained conjugate gradient algorithm. Conditions for optimum spatial resolution are found by analysis of a derived radiometric transfer function and correspond to superficial chromophores and/or weak infrared absorption in a laser irradiated biological material. Analysis indicates that if the infrared attenuation coefficient is sufficiently small (i.e., less than 10mm-1), infrared radiometry in combination with a deconvolution algorithm allows estimation of lateral physical dimensions of laser heated subsurface chromophores in human skin.

Algorithms↗
PubMed2002

A novel design of thermal anomaly for mammary gland tumor phantom for microwave radiometer.

Microwave radiometry is the spectral measurement technique of resolving electromagnetic radiation of all matters which temperature is above absolute zero. This technique utilizes the electromagnetic noise field generated by a thermal volume similar to a mechanism existing in biological tissues. One particular application of microwave radiometry is for analyzing temperature differentials of inside of human body to detect and diagnose some crucial pathological conditions. For the general evaluation of a microwave radiometer, we propose a new type of phantom containing a mammary gland tumor imitator by considering biological heat diffusion effects propagated by a real tumor. Theoretical researches of human tumor revealed the fact that temperature distribution of tissues around a tumor formed a Gaussian statistics. To comply with the physiological property of the real tumor, we built a mammary gland tumor imitator composed of two parts (pseudotumor and thermal anomaly) and observed its temperature distribution when it was placed inside a phantom. Our results showed that the thermal properties of tumor imitator well agreed with heat-transfer properties of a real tumor and the proportional linear relationship existed between the location of tumor imitator and the intensity of radiometer measurements. From this relationship, we could also estimate several parameters related with our phantom, such as the minimum detectable size and maximum detectable depth of a tumor imitator.

Hot Temperature↗
PubMed1992

Early detection of extravasation of radiographic contrast medium. Work in progress.

Microwave radiometry is a passive and noninvasive technique that allows quick detection of subcutaneous temperature changes. The feasibility of this technique for differentiating normal intravenous infusions of radiographic contrast medium from extravasations of contrast medium was tested in anesthetized dogs. Room-temperature and heated ionic and nonionic contrast media were administered at flow rates ranging from 0.2 to 9.9 mL/sec by means of a power injector. On the basis of these experiments, an algorithm to adjust for extravasation detection thresholds as a function of injection flow rates was developed. With this algorithm, results showed a false-positive rate of 0% at all infusion rates and false-negative rates of 2%, 2%, and 4% at pump speeds of 0.2, 1.0, and 9.9 mL/sec, respectively. The times of these extravasation "alarms" corresponded to maximum extravasated volumes, respectively, of 4, 6.5, and 8 mL. Microwave radiometry has clinical potential for early detection of extravasation of contrast medium administered with power injectors.

Algorithms↗
PubMed1987

[57Co-bleomycetin distribution in the body of experimental animals with hyperglycemia].

Distribution of 57Co-bleomycetin in organs and tissues of rats with experimental short-term hyperglycemia was studied. Hyperglycemia was induced by intraperitoneal administration of 40 per cent glucose solution in doses of 1 to 10.4 g/kg. The labeled antitumor antibiotic was also administered intraperitoneally (0.2-0.8 MBq per animal). The data on both the external radiometry in the area under the animal limb and the radiometry of separate organs and tissues showed that hyperglycemia markedly altered pharmacokinetics of the labeled antibiotic and retarded its elimination. With respect to the lungs it even increased the drug tropism and accumulation. This information may be useful in radionuclide diagnosis and therapy in particular of lung cancer. The time course of glucose concentration in blood was not an adequate criterion of hyperglycemia influence since the influence of hyperglycemia on retarding the drug elimination was also observed when the level of glucose in blood did not differ from the initial one.

Animals↗
PubMedDate not supplied

Autoradiographic and biochemical studies of drug distribution in the liver. I. [14C]Dehydrocorydaline.

Whole body autoradiography revealed that the distribution pattern of [14C]dehydrocorydaline in the mouse and rat liver was heterogeneous (or reticular) regardless of time after intravenous administration of the labeled agent. Microautoradiography by dry-mounting method revealed that the macroscopic heterogeneous pattern was due to the periportal localization of the radioactive compound in the hepatic lobule. By comparison with [14C]salicylid acid, [14C]diphenylhydantoin and [14C]p-chlorophenoxyacetic acid whose distribution pattern are homogeneous in the liver, the present studies indicated that the existence and persistence of heterogeneous distribution of [14C]dehydrocorydaline in the liver had the following causes: 1. Shortly after intravenous administration, the amount of [14C]dehydrocorydaline circulated to the liver was greatly restricted by its significant distribution in non-hepatic tissues. This was shown by the whole body autoradiography, radiometry of tissues and quantitative comparison of volumes of distribution in non-hepatic tissues. Therefore, 2. perilobular hepatocytes alone could take up [14C]dehydrocorydaline and consequently, centrilobular cells were unavailable to it: heterogeneous distribution pattern is formed. This was shown by microautoradiography as described above, and by the rapid and significant uptake of [14C]dehydrocorydaline by isolated hepatocytes in vitro and by the liver to which the labeled agents were continuously administered in situ. It was also substantiated by the more homogeneous distribution pattern in the liver of the rat to which greater amount of [14C]dehydrocorydaline was gradually given into the portal vein and of the mouse with allyl formate-induced perilobular damage. 3. Redistribution of [14C]dehydrocorydaline scarcely occurred in the whole body and therefore radioactive substance was not significantly supplied to the liver: the distribution pattern remained unchanged. This was shown by the whole body autoradiography and radiometry of tissues.

Alkaloids↗
PubMedDate not supplied

Autoradiographic and biochemical studies of drug distribution in the liver. II. [35S]Chlorpromazine and [14C]imipramine.

Whole body autoradiography revealed that the distribution pattern of [35S]chlorpromazine and [14C]imipramine in the mouse and rat liver was heterogeneous (or reticular) shortly after intravenous administration of the labeled agents and then became homogeneous. Microautoradiography by dry-mounting method revealed that the macroscopic heterogeneous pattern of [35S]chlorpromazine was due to its periportal localization in the hepatic lobule. The present studies indicated that the heterogeneous distribution was re-arranged to a homogeneous one in the following way: 1. The amount of [35S]chlorpromazine and [14C]imipramine circulated to the liver was greatly restricted by their significant distribution in non-hepatic tissues shortly after administration. This was shown by whole body autoradiography, radiometry of tissues and volumes of distribution in non-hepatic tissues. Therefore, 2. perilobular hepatocytes alone could take up the agents and consequently, centrilobular cells were unavailable to them: heterogeneous distribution pattern is formed. This was shown by microautoradiography described above, and by the rapid and significant uptake of the agents by isolated hepatocytes in vitro and of [35S]chlorpromazine by the liver to which the agent was continuously administered in situ. However, 3. re-distribution of [35S]chlorpromazine and [14C]imipramine occurred thereafter. Therefore, the radioactive compounds were significantly supplied to the liver late after administration: the pattern became homogeneous. This was shown by the whole body autoradiography and radiometry.

Animals↗
PubMed1998

Temperature controlled high energy transurethral microwave thermotherapy for benign prostatic hyperplasia using a heat shock strategy.

PURPOSE: We evaluate the clinical outcome of temperature controlled high energy transurethral microwave thermotherapy for benign prostatic hyperplasia using heat shock strategy. MATERIALS AND METHODS: A total of 32 patients were evaluated 3, 6 and 12 months after thermotherapy according to symptom scores, uroflowmetry, residual urine volume, sexual functions and side effects. RESULTS: At 12 months symptom score and maximum flow rate had improved 79% from 13.5 to 2.9, and 71% from 10.0 to 17.1 ml. per second, respectively. Furthermore, bother and quality of life scores and residual and voided urine volumes had improved significantly. However, a higher morbidity than previously shown after lower energy protocols was demonstrated. Treatment influenced sexual functions, especially ejaculation quality, and after treatment 29% of the patients had anejaculation. Significantly less energy was required for prostate volumes 40 ml. or greater to reach the same intraprostatic temperature level as those less than 40 ml. as demonstrated by radiometry. CONCLUSIONS: High energy transurethral microwave thermotherapy using a heat shock strategy is an effective treatment for benign prostatic hyperplasia and produces a better outcome than shown with lower energy protocols. However, the morbidity is not negligible and ejaculation quality is affected. Less relative energy is needed for large than small prostate volumes to reach the same intraprostatic temperature level as demonstrated by radiometry.

Ejaculation↗
PubMed1994

Optical and thermal characterization of natural (Sepia officinalis) melanin.

The optical properties and the thermal diffusivity of natural cuttlefish (Sepia officinalis) melanin have been measured. The optical absorption and scattering properties of melanin particles were determined at 580 nm and 633 nm, using photometric and photothermal techniques. For the photometric studies, the absorption and the transport scattering coefficients were determined from the measurements of diffuse reflectance and transmittance. The scattering anisotropy was obtained from an additional measurement of the total attenuation coefficient and independently obtained by goniometry. For photothermal studies, pulsed photothermal radiometry was used to deduce the absorption and transport scattering coefficients via a model based on optical diffusion theory. Pulsed photothermal radiometry was also used to provide the thermal diffusivity of solid melanin pressed pellets.

Animals↗
PubMed1984

Disposition of radiolabeled imipenem and cilastatin in normal human volunteers.

In the first of two successive studies, four healthy male subjects received 500 mg of 14C-labeled imipenem alone and together with 500 mg of unlabeled cilastatin sodium. In the second study, the same subjects were given 250 mg of 14C-labeled cilastatin sodium alone and together with 250 and 1,000 mg of cold imipenem. Concentrations of imipenem and cilastatin in plasma, urine, and feces were assayed by high-pressure liquid chromatography and radiometry. Plasma concentrations of imipenem assayed radiometrically were higher than those measured by high-pressure liquid chromatography. In one subject studied at the end of drug administration, the open lactam metabolite of imipenem represented 9% of the radioactivity. Plasma levels of cilastatin determined by high-pressure liquid chromatography and radiometry were virtually identical. Urinary recovery of imipenem varied between 12 and 42% of the dose when that drug was given alone but increased to between 64 and 75% when administered with cilastatin sodium at a 1:1 ratio. Almost all radioactivity of imipenem was recovered in the urine within 96 h after drug administration. The open lactam metabolite, resulting from the metabolism of imipenem in the kidneys by a dipeptidase, dehydropeptidase-I, represented 80 to 90% of the effluent radioactivity when imipenem was given alone and about 20% when cilastatin sodium was coadministered. Renal excretion of cilastatin followed closely that of imipenem. Almost all of the administered radioactivity was recovered in 24 h, and about 75% of the dose was recovered as unchanged cilastatin within 6 h. The N-acetyl metabolite of cilastatin was found to represent about 12% of the total radioactivity.

Adult↗
PubMed1989

[Radionuclide study of fat absorption in the small intestine].

Analysis of the use of a simple and effective method for the assessment of intestinal fat absorption with the help of external radiometry of the abdominal area using a gamma-radiation collimated detector and whole body radiometry has shown that a coefficient of intestinal fat absorption in patients in the preoperative period does not demonstrate a statistically significant difference from the respective normal one, and gastrectomy with placing esophago-cecal anastomosis disabling the duodenum, leads to considerable deterioration of fat absorptive function.

Dietary Fats↗
PubMed1986

[Radiation doses to patients after the use of 99mTc-pyrophosphate and 113mIn-indifor].

The doses of irradiation of patients during the use of 99mTc-pyrphotech and 113mIn-indifor have been defined on the basis of their pharmacokinetics. The data has been obtained with the use of radiometer of human radiation, the method of organs screening during radiometry, and of the gamma-camera and blood samples radiometry. The calculations have been performed in accordance with the known method based on the heterogeneous model of the "standard" human. In the dose calculations for bone tissue and for the red marrow the dosimetry model is used and the values of absorbed fractions recommended by the ICRP. The absorbed and equivalent doses of irradiation of different organs and systems in human organism have been defined. The required values of quality index have been calculated using the spectrum of absorbed dose on the scale of linear transfer of energy for all radiations of the analysed nuclides. The obtained values of efficient equivalent dose are 8.6 and 16 MeV/MBq for 113mIn-indifor and 99mTc-pyrphotech correspondingly.

Bone Marrow↗
PubMed1987

[Pharmacokinetics of 99mTc-technephore in man].

Assessment of the pharmacokinetics of 99mTc-technephore in the human body was based on an analysis of the results of its study in 43 out of 87 patients with neoplasms of non-osteogenic origin (breast cancer, lung cancer, reticulum cell sarcoma, etc.). Radiometry by means of a counter of the whole human body radiation was performed shortly after the drug administration with one-hour intervals for 4-5 hours. Methods of blood radiometry and osteoscintigraphy were employed. The study showed that the redistribution of the drug occurred in the first minutes after its injection, chiefly between the 2 volumes: the skeleton and the urinary system. The value of its activity in the bladder by the 3rd hour was 59% of the administered amount. Clearance of the blood was rapid and its radioactivity by the 3rd hour was no more than 6% of the administered amount. The amount of the drug by the same time was within 31-32%. A high gradient of differential accumulation of the drug in the osseous tissue and the adjoining tissues (the skeleton/background-312%) made it possible to get high-quality scintigrams. Investigations of the patients with the help of gamma-chambers and scanners were initiated 2.5-3 hours after the drug injection. The sensitivity and specificity of 99mTc-technephore were similar to those of other phosphatic and phosphonate radiopharmaceuticals: 96 and 12%. A conclusion was made that the drug could be used in clinical practice as an osteotropic agent.

Humans↗
PubMed1986

[Radionuclide study of absorption in the intestines in acute poisonings].

A study was made of the intestinal absorption of 131I-oleic acid and human serum 131I-albumin in patients with acute exogenous intoxications and endogenous intoxications caused by acute intestinal ileus using the method of external radiometry of the abdominal parts. The utmost disorders of absorption were noted in patients with an average and grave degree of exogenous intoxication as well as in patients with complete occlusion ileus. Absorptive intestinal capacity in most of the patients improved as a result of therapeutic measures. A rapid method for the evaluation of absorption power was developed and compared with the method of external radiometry of the abdominal parts. An equation of regression was derived making it possible to determine values of the parameter of a period of drug semiabsorption using the rapid method values.

Acute Disease↗
PubMed1983

[Increased information value of the radiophosphorus diagnosis of pigmented skin neoplasms].

A complex of new methods are proposed. They make it possible to improve the precision and informative value of the results of 32P diagnosis of pigmental skin tumors. The following methods are used: 1) fractional administration of the indicator to increase the level of 32P accumulation in melanomas; it made it possible to improve the differential-diagnostic capacity of the radiophosphorus test; 2) beta-radiometry of pathological and control skin zones with and without fine tissue equivalent filters to "contrast" tumors and to determine the average depth of their invasion to unchanged tissues; the use of this method made it possible to lessen the number of false-negative diagnoses and to get additional clinicodiagnostic information that can be useful in the planning of surgical and radiation treatment; 3) radiometry of skin zones in the spectrometric regimen with three different levels of the integral discrimination of beta-radiation impulses to determine the thickness and lower line of the layer of the abnormal accumulation of the indicator in the pathological skin zone; the use of this method makes it possible to detect incrusted melanomas.

Diagnosis, Differential↗
PubMed1978

[Comparative evaluation of modern intraoperative diagnostic methods in malignant gliomas of the brain].

The following methods were employed: Intravital staining with bromphenol blue (70 patients), radiometry with P 32 (127 patients), echo encephalography (12 patients,) puncture biopsy (18 patients), rheometry (96 patients). Bromphenol blue is injected into the a. cerebri media or the supraclinoidal a. carotis interna and stains the periphery of malignant tumours and the entire tissue of benign tumours. Radiometry also serves for the intraoperative finding of tumour remainders which must be located at least 20 to 22 mm below the cortex of the brain. Tumour biopsy was carried out with a sharp cannula to avoid deformation of the tissue cylinder. Rheometry proved to be very useful when avoiding the mixing with blood, liquor, and cyst fluid at the measuring tip.

Biopsy, Needle↗