Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Photometry”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources
PubMed1981

[Control of low-dose heparin therapy using photometry to detect biologically active heparin].

The low-dose heparin prophylaxis depends upon a low-level activation of antithrombin III to prevent thrombin generation. For the routine regiment, the application of 5000 units twice daily seems sufficient to reduce fatal lung embolism. By comparing three commercially available heparins (Thrombophob, Thrombo-Vetren, Heparin-Dihydergot) the effectiveness of the so-called low-dose heparin application was controlled with a chromogenic substrate assay (Coatest, Kabivitrum). Only twice-daily Heparin-Dihydergot resulted in an average heparin level of 0.12 +/- 0.78 m/ml plasma, which was sufficient to provide an effective thrombosis prophylaxis.

Adult↗
PubMed1981

An instrument for digital matrix photometry.

A new instrument was conceived and designed for quantitative measurement of chromophoric areas or colored spots such as are produced in (e.g.) thin-layer chromatography. The areas to be measured are subdivided grid-like into small subunits, and the absorbance of each of these is measured. The sum of absorbances for all subunits is directly proportional to the total amount of light-absorbing substances in a spot. The absorbances of the subunits are measured with a photodetector that contains hundreds of microscopically small photodiodes, arranged in a precise geometric array. The photodiode array is interfaced with a computer via an analog-to-digital converter for numerically integrating the individual signals from each photodiode. With this analytical system, quantitation of light-absorbing substance is accurate and precise for areas of different sizes, shapes, and internal irregularity.

Chromogenic Compounds↗
PubMed1994

[Anti-inflammatory effect of a local combination therapy with diclofenac and prednisolone vs. indomethacin and prednisolone. A laser flare cell photometry study].

UNLABELLED: The nonsteroidal anti-inflammatory agent diclofenac (Voltaren) has recently become commercially available in form of 0.1% eyedrops (Voltaren ophtha). In the present study, we compared the anti-inflammatory effect of a topical combination therapy with diclofenac and prednisolone vs. indomethacin and prednisolone. PATIENTS AND METHOD: The FC-1000 laser flare-cell photometer (Kowa) was used to investigate 40 patients before and after cataract surgery with IOL implantation. This method allows quantitative in vivo determination of aqueous flare and aqueous particle concentration. The patients were randomly assigned to one of the following two treatment protocols: Protocol A: diclofenac 0.1% eyedrops and prednisolone 1% eyedrops (Inflanefran forte); protocol B: indomethacin 1% eyedrops (Chibro-Amuno 3) and prednisolone 1% eyedrops. One drop of either drug was administered 4 times per day to each patient. Treatment with nonsteroidal agents started on the day before surgery, whereas prednisolone treatment started immediately at the end of surgery. No parabulbar or oral steroids were administered. RESULTS: In group A (diclofenac and prednisolone), the flare (in photon counts/ms) increased from a preoperative value of 10 +/- 4.3 (mean +/- SD) to 36.7 +/- 19.3 on the 1st postoperative day. This value is significantly (P < 0.05) higher than in group B (indomethacin and prednisolone) on the 1st postoperative day: 27.4 +/- 9.4. The aqueous particle concentration on day 1 after surgery was also significantly (P < 0.01) higher under treatment with diclofenac and prednisolone than with indomethacin and prednisolone (44.3 vs 26.3 particles/0.075 mm3, respectively). On the 3rd postoperative day, the differences between the two treatment groups were no longer present. CONCLUSIONS: In the early postoperative period after cataract surgery, the anti-inflammatory effect of a topical combination therapy with diclofenac and prednisolone is weaker than that of indomethacin and prednisolone. However, this difference is no longer observed on day 3 after surgery, so that there is probably no major difference in clinical outcome between the two treatment protocols.

Aged↗
PubMedDate not supplied

Method of noninvasive and continuous hemolysis/thrombogenesis measurement by laser photometry during artificial heart development.

The purpose of this research is to propose and develop a method to measure hemolysis and thrombogenesis non invasively and continuously to aid in development of an artificial heart. Generally, the optical absorption rate of hemoglobin is influenced by oxygen saturation except at the isosbestic point, which is not influenced by oxygen saturation. The authors, therefore, used an 805 nm laser diode, an optical spectrum analyzer to obtain greater accuracy. An experimental blood circuit system was constructed using a Bio-Pump, Tygon tubing, a soft shell reservoir, and an optical measurement system. Experimental settings for monitoring hemolysis were as follows; blood volume 200 ml, blood flow 6 L/min, and afterload 200 mmHg. Blood was sampled six times (0, 30, 60, 120, 180, and 240 min), and hemolysis in each sampled was measured using a colorimetric method. Comparing continuous laser measurement data with the sample data, an adequate correlation is obtained, proving that the dynamic trend of hemolysis could be continuously measured. Furthermore, to analyze the process of thrombogenesis, simple experiments were performed using blood neutralized by protamine. As a result, the authors could see the process of thrombogenesis as it occurred and could confirm that this method is able to dynamically detect hemolysis and thrombogenesis.

Biomedical Engineering↗
PubMed1998

Use of laser flare-cell photometry to count anterior chamber canine leukocytes and latex beads in vitro.

OBJECTIVE: To determine whether the cell measuring function of a laser flare-cell photometer is accurate and reproducible, using an in vitro model. SAMPLE POPULATION: Leukocytes from 8 clinically normal Beagles. PROCEDURE: Latex beads 11.9 and 6.4 microm in diameter were used to simulate canine WBC and RBC, respectively. Beads were diluted to known concentrations, placed in a model eye, and counted by use of the laser flare-cell photometer. A range of protein diluents from 0 to 2,000 mg/dl was used to suspend beads and simulate anterior uveitis, when cells and protein would be in the aqueous humor. A similar series of experiments were repeated, using leukocytes isolated from the blood of Beagles. RESULTS: The laser flare-cell photometer can count 6.4-microm beads reproducibly and linearly up to a total of 510 cells/mm3, and 11.9-microm beads up to 1,300 cells/mm3 over a protein range of 0 to 2,000 mg/dl. The instrument can also count canine leukocytes reproducibly and linearly up to 1,300 cells/mms over that protein range. CONCLUSIONS AND CLINICAL RELEVANCE: Cell and bead sizes and concentrations and protein concentrations were chosen to mimic the range observed in dogs with uveitis. Because the laser flare-cell photometer accurately counted these cells in a range of protein concentrations in the model eye, it has the potential for use in noninvasive quantitative evaluation and monitoring of uveitis in dogs.

Animals↗